Industry Spotlight

Industry Spotlight
Industry Spotlight
Researchers used ANSYS
simulation technology to develop
a housing for satellite electronic
circuits that is 30 percent lighter
than comparable structures.
The latest addition to the ANSYS
family, FLUENT 6.3 offers new
CFD solver, modeling and other
options.
ANSYS CFX software improves
the design of a hydro-generator
for use in remote areas.
Contents
Industry Spotlight
Departments
6 Factory and Plant
Editorial
Equipment
Tools for Product and Process Innovation
Simulation-driven design plays a
major role in developing industrial
machines for manufacturing and
process facilities around the world.
...................
2
Industry News
Announcements and Upcoming Events
.........................
3
Guest Commentary
Features
Integrating CAD and CAE to Enable
Simulation-Driven Design
...................................................................
11 ANSYS, Inc. Welcomes
23
Simulation at Work
Fluent Inc.
CFD Simulation Recreates Aviation History
ANSYS broadens its opportunities
to provide leading-edge engineering
solutions with the acquisition of
Fluent Inc.
Weight-Optimized Design of a Commercial
Truck Front Suspension Component
26
Developing Construction Products
with Better Fire Performance
28
...............
..................................
.........................................................
Technology Update
14 FLUENT 6.3: Major
Bringing High-Performance Computing
to the Mainstream
Advances in CFD Simulation
.....................................................................................
The latest addition to the ANSYS
family features new solver, modeling
and other options — resulting in
greater speed and flexibility.
..............................................
Brings Electrical Power
to Rural Areas
ANSYS CFX software improves the
design and efficiency of a small
hydro-generator for use in remote
areas of developing countries.
.............................
About the cover
Companies in the factory and
plant equipment market use
engineering simulation extensively, meeting the challenges
of developing cost-effective,
high-precision and efficient
industrial machines that
must operate under harsh
conditions. Read more in
this issue’s Industry Spotlight
article beginning on page 6.
For ANSYS, Inc. sales information, call 1.866.267.9724, or visit www.ansys.com.
To subscribe to ANSYS Solutions, go to www.ansys.com/subscribe.
Editorial Director
John Krouse
[email protected]
Designers
Miller Creative Group
[email protected]
Ad Sales Manager
Beth Mazurak
[email protected]
Editorial Advisor
Kelly Wall
[email protected]
Managing Editor
Fran Hensler
[email protected]
Art Director
Dan Hart
[email protected]
Circulation Manager
Elaine Travers
[email protected]
Editorial Contributor
Chris Reeves
[email protected]
ANSYS Solutions is published for ANSYS, Inc. customers, partners and others interested in the field of design and analysis applications.
Neither ANSYS, Inc. nor the editorial director nor Miller Creative Group guarantees or warrants accuracy or completeness of the material contained in this publication. ANSYS,
ANSYS Workbench, CFX, AUTODYN, FLUENT and any and all ANSYS, Inc. product and service names are registered trademarks or trademarks of ANSYS, Inc. or its subsidiaries
located in the United States or other countries. ICEM CFD is a trademark licensed by ANSYS, Inc. All other trademarks or registered trademarks are the property of their respective
owners. POSTMASTER: Send change of address to ANSYS, Inc., Southpointe, 275 Technology Drive, Canonsburg, PA 15317 USA.
©2006 ANSYS, Inc. All rights reserved.
www.ansys.com
33
Tips and Techniques
Working with Coupled-Field Elements
Satellite Components
20 CFD Simulation
30
Tech File
Running Solutions from Macros
16 Analyzing Composites for
Researchers used ANSYS software
to study the behavior of a composite
housing for electronic circuits and
quickly developed a design nearly
30 percent lighter than a comparable
aluminum structure.
24
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Volume 7, Issue 4 2006
35
Editorial
2
Tools for Product and Process Innovation
Simulation technology enables companies to stand out from the crowd with
knock-out designs and leading-edge product development processes.
Innovate or evaporate. That’s
the new business imperative.
Until recently, getting a product
to market faster, cheaper and
better than the competition
usually was good enough.
Not anymore. Now — in addition to time-to-market, cost and
quality — manufacturers must
focus on innovation: designs
that take the market by storm
By John Krouse
Editorial Director
and leading-edge development
ANSYS Solutions
processes that transform
[email protected]
conceptual ideas into saleable,
reliable and cost-effective
products.
Products must stand apart from others, breaking
new ground in performance, size capacity or other
attributes that compel consumers to pick a particular
item from among many, or that influence OEMs to do
business with one supplier over another. In many
cases, companies improve existing products with
imaginative functions and enhancements. Other times
they create whole new classes of products that totally
dominate a market segment as competitors scramble
to catch up. In a world economy of radical change and
fast-moving trends, innovation has emerged as the big
market differentiator.
Innovation is clearly on the minds of top executives, as reflected in a second annual survey on the
topic conducted by The Boston Consulting Group in
conjunction with BusinessWeek magazine. They
received input from 1,000 senior managers worldwide,
making it their “deepest management survey to date
on this critical issue.” The report, “The World’s Most
Innovative Companies,” discusses the importance of
design as a differentiator as well as how companies
are rewiring themselves to operate differently, with
72 percent of senior executives in the survey naming
innovation as one of their top priorities.
One of the most interesting parts of the report is a
list of the top 25 innovative companies. Of the top 20,
14 are industrial companies — and ANSYS users. The
others include a coffeehouse chain, retail stores, air-
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lines and Internet firms. Last year’s list reflected much
the same.
The use of ANSYS by the world’s most innovative
companies comes as no surprise, of course.
Simulation-driven design is the basis for innovative
development processes and product concepts at a
wide range of companies in nearly all manufacturing
industries. The ability to quickly perform what-if
studies and readily evaluate alternative designs
gives engineers valuable insight into product behavior,
lets them make intelligent trade-off decisions and
provides the freedom not only to imagine way-out
ideas but to easily test their feasibility. Design
optimization and sensitivity studies augment
engineering creativity and serve as guides to creative
solutions that are not always intuitively obvious.
Using these and other wide-ranging capabilities,
virtual prototyping can simulate an entire system or
subsystem in its operating environments to study and
refine real-world product performance, thus enabling
engineers to develop workable innovative designs for
products that otherwise might turn out to be flops in
the market because of performance, warranty or
reliability issues. Moreover, visualization of analysis
results that vividly depict product performance
facilitates close collaboration and synergy between
members of multidisciplinary teams in which people
synergistically create imaginative design concepts
that might not have surfaced otherwise.
In this manner, simulation-driven design leverages the creativity of engineers and the intellectual
capital of the enterprise. This elevates the approach to
a strategic role as an innovation enabler, allowing
manufacturers who make smart use of the technology
to establish their brand value, strengthen their market
position and boost top-line revenue growth by
developing winning products.■
ANSYS Solutions
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Volume 7, Issue 4 2006
Industry News
Recent Announcements
and Upcoming Events
ANSYS Chosen as CAE Software for Chinese
Mechanical Design Engineer Qualification
ANSYS Software Offers 64-bit Support for
Microsoft Windows Compute Cluster Server 2003
The Chinese Mechanical Engineering Society (CMES)
and the Examination Center of Ministry of Education
have formally incorporated ANSYS software into
China’s national Mechanical Design Engineer (MDE)
qualification examination. MDE certification was begun
in China in April 2006. It is designed to improve the skill
level of professionals in the Chinese manufacturing
sector, which also widely uses ANSYS software for
computer-aided engineering (CAE).
The upcoming releases of ANSYS multiphysics
simulation software — ANSYS 11.0 and FLUENT 6.3
— will include support for Microsoft Windows
Compute Cluster Server 2003. Enabling high-performance computing (HPC) on the Microsoft Windows
platform, the new solution helps customers deploy
computer-aided engineering at a higher level than in
the past, decreasing the time required for simulations
and increasing the accuracy of results.
CMES is a professional society engaged in promoting
the art and science of mechanical engineering
throughout its host nation. In 2005, the Mechanical
Design Institution (MDI) of CMES approached ANSYS
China about using the software in developing a
standard examination to certify mechanical engineers.
ANSYS 11.0 and FLUENT 6.3 take advantage of the
Microsoft Message Passing Interface (MPI) software
layer in Windows Compute Cluster Server 2003 for
data communication between processors on the
cluster. The new releases also use the Microsoft Job
Scheduler in Windows Compute Cluster Server 2003,
providing an off-the-shelf solution for launching and
controlling jobs on the cluster.
The first-ever MDE qualification examination was held
in test centers located in eight Chinese provinces, with
619 students from more than 20 renowned universities
participating. More than 400 passed the exam and
received the MDE qualification certificate.
ANSYS Named to Honor Roll
ANSYS, Inc. has been named to the software industry
Sustained Success Honor RollTM for the third consecutive year. Culled from a list of more than 500 public
software companies compiled annually by Cape Horn
Strategies, ANSYS is one of 20 that made the 2006
honor roll.
Companies included in the list have an outstanding
record of growing profitability for the past five
consecutive years or more. With 10 consecutive years
of profitable growth, ANSYS is the only engineering
simulation software company that made the Sustained
Success Honor Roll, as well as one of only eight
software companies that reported at least 10 consecutive years of growing profitability. According to analysis
firm Cape Horn Strategies, honor roll members
significantly outperformed industry averages.
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Fluent CAD Connection Software Facilitates Link
between Design and Simulation
The recently released Fluent Connection 1.1 software
helps streamline the process of creating simulation
models based on design data from leading computeraided design packages. Integrating core CAE
technologies with the most popular independent
design tools has been a key part of the ANSYS
strategy for nearly a decade; this latest release brings
direct integration to the Fluent products as well.
Fluent Inc. recently was acquired by ANSYS, Inc.
The Fluent UGS-NX TM Connection, Fluent Pro/
ENGINEER ® Wildfire ® Connection and Fluent
Solidworks® Connection products operate within the
CAD system user environments and provide tools for
checking and conditioning the 3-D geometry model in
order to ensure that it has been properly prepared for
the next step in the simulation process. Using Fluent
Connection, CAD users can eliminate or repair
geometry issues that would otherwise impede the
simulation process. By providing a well-defined way
to check the CAD model for possible simulationrelated issues, Fluent Connection helps engineering
organizations ensure a streamlined hand-off between
CAD and simulation.
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Volume 7, Issue 4 2006
3
Industry News
4
Upcoming Events
EuroBLECH – 19th International Sheet Metal
Working Technology Exhibition
Hanover, Germany
October 24 – 28, 2006
www.euroblech.com
24th CADFEM Users’ Meeting
Stuttgart, Germany
October 25 – 27, 2006
www.usersmeeting.com/index.21.0.html
ANSYS Users Conference
San Miguel de Allende, México
October 26 – 27, 2006
www.grupossc.com
Italian ANSYS User Conference
Stezzano, Italy
November 9 – 10, 2006
http://meeting2006.enginsoft.it
ANSYS User Conference
Bangalore, India
November 9 – 10, 2006
www.ansysindia.com/index.htm
ANSYS Latin American User Conference
Florianopolis, Brazil
November 9 – 10. 2006
www.esss.com.br/ansys2006
2006 Korea ANSYS CFX User Conference
Pusan, Korea
October 26 – 27, 2006
www.anst.co.kr
Fluent Germany Forum 2006
Bad Nauheim, Germany
November 14, 2006
www.fluent.com/worldwide/germany/support/ugm/
index.htm
Taiwan ANSYS User Conference
Taipei, Taiwan
October 30 – 31, 2006
www.cadmen.com
Electronica 2006 – Components Systems Applications
Munich, Germany
November 14 – 17, 2006
www.global-electronics.net/?id=20307
ANSYS User Conference
Singapore
November 2 – 3, 2006
www.cadit.com.sg
Japan ANSYS User Conference
Tokyo, Japan
November 15 – 16, 2006
www.cybernet.co.jp
Benelux ANSYS User Conference
Breda, Netherlands
November 3, 2006
www.infinite.nl
Fluent Asia Pacific Users’ Group Meeting
Tokyo, Japan
November 16 – 17, 2006
www.fluent.co.jp
China ANSYS User Conference
Sanya, China
November 6 – 8, 2006
www.ansys.com.cn/conference/con_06
Fluent Italy Forum 2006
Milan, Italy
November 21, 2006
www.fluent.com/worldwide/italy/support/ugm06
ANSYS User Conference
Rio de Janiero, Brazil
November 7 – 8, 2006
www.softec.com.br
ANSYS User Conference
Melbourne, Australia
November 21 – 22, 2006
www.leapaust.com.au
MicroMachine Conference
Tokyo, Japan
November 7 – 9, 2006
www.cybernet.co.jp
Fluent Forum 2006
Madrid, Spain
November 24, 2006
www.fluent.com/worldwide/spain/events/forum06.htm
Fluent France Forum 2006
Paris, France
November 9, 2006
www.fluent.com/worldwide/france/support/ugm06/
index.htm
Euromold 2006 – World Fair for Moldmaking &
Tooling, Design & Application Development
Frankfurt, Germany
November 29 – December 2, 2006
www.euromold.com/splash/splash_em.html
www.ansys.com
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Volume 7, Issue 4 2006
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Industry Spotlight
6
From small job shops to giant superfactories and processing plants, facilities throughout the
supply chain use production equipment to turn raw materials into products in the automotive,
aerospace, telecommunications, electronics, heavy equipment, consumer products,
petrochemical, pharmaceutical and food processing sectors, and even in service industries
such as data processing, finance and insurance.
Images courtesy Hatch Australia.
Factory and
Plant Equipment
By Achuth Rao
Product Manager
ANSYS, Inc.
Simulation-driven design plays a major role in
developing industrial machines for manufacturing
and process facilities around the world.
To keep up with the increasing demand for
manufactured products, companies rely on factory
equipment including machine tools, injection
molding equipment, robots, material handling
equipment, stamping machines, welders and other
industrial machines.
www.ansys.com
In the competitive drive for factories and plants to
produce more with less, the increased speed and
efficiency of today’s technology-based equipment is
credited as a major element in industrial productivity
gains. According to the National Association of
Manufacturers, manufacturing productivity grew
4.8 percent last year. That’s a 78 percent jump
compared to the economy as a whole and amounts to
a 24 percent increase during the past four years.
So to remain competitive, companies around the
world invest heavily in the latest state-of-the-art
production equipment.
Statistics from the Manufacturing Performance
Institute indicate that 20 percent of sales are
re-invested in factory capital equipment in China, for
example, and that 45 percent of U.S. plants expect to
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Volume 7, Issue 4 2006
7
increase their spending on production equipment in
2006. According to the World Machine Tool Output
and Consumption Survey, Japan ranks number one in
terms of world output of machine tools and second in
usage of this equipment. Meanwhile, figures from
financial services firm JPMorgan specify that the rate
of manufacturing expansion in the European sector is
reaching a six-year high.
On the flip side, industrial equipment buyers have
a long list of demanding requirements. Machines must
operate for decades under harsh conditions and often
for multiple shifts, seven days a week. Downtime is
unacceptable, since daily revenue losses can run into
millions of dollars when production is halted. Energy
efficiency is mandatory in lowering operating costs in
the face of rising electric utility prices. Noise emissions
must be low to meet strict regulatory standards.
Vibrations must be minimized to avoid fatigue failures
and unwanted resonances in precision machines.
In addition, equipment must be cost-sensitive; new
models must be launched quickly to meet fierce
global competition.
Companies in the factory and plant equipment
market regard engineering simulation as an indispensable tool in meeting these challenges. ANSYS
technology in particular is used by many of these firms
in their product development cycle. A range of
leading-edge solutions provides a breadth and depth
of analysis capabilities including meshing of complex
parts and assemblies, computational fluid dynamics
(CFD), optimization, structural and thermal tools, and a
wide range of multiphysics solutions. The ANSYS
Workbench environment brings these technologies
together in a unified suite of software.
www.ansys.com
Boosting Machine Speed and Capacity
Simulation technology plays a key role in efforts
around the world to make industrial equipment more
productive in terms of machine capacity as well as
operational speed. Spain-based technological
research center Fundacion ITMA, for example,
performed a coupled thermo–structural analysis with
ANSYS Mechanical software in developing a new
design for a steel-making ladle — resulting in a 15
percent greater capacity for handling liquid metal.
Likewise, metalworking equipment manufacturer
Gebr. Heller Maschinenfabrik GmbH in Germany uses
ANSYS Mechanical in static, dynamic and thermal
simulations of the metalworking equipment it
develops, which includes transfer lines, machining
centers, flexible manufacturing systems, and milling
An ANSYS simulation model is superimposed on a representation
of a Heller milling machine for manufacturing heavy truck
crankshafts and camshafts. The handling system automatically
transports the crankshafts into and out of the milling machine.
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Volume 7, Issue 4 2006
Industry Spotlight
8
ANSYS Workbench was used at Robo-Technology in developing a system in which two precision robots work together in ultrasonic
testing of helicopter parts up to six meters in length.
and broaching machines. Typical simulations include
deformation of parts, modal analysis and frequency
response of the machines together with tools and
workpieces, structural temperature distribution and
topology optimization. In one recent application, Heller
credits ANSYS simulation in achieving a 20 percent
increase in operational productivity of a machining
center for the production of automotive parts such as
engine blocks, cylinder heads, transmission housings
and chassis components.
Building Better Robots
According to the Robotic Industries Association, nearly
1 million robots populate global manufacturing, with
almost half working in Japan. Robots perform a wide
range of production tasks including material handling,
workpiece and tool positioning, arc and spot welding,
packaging, and process applications such as inspection, testing, spraying and dispensing. Simulation is
critical in developing these versatile machines for
optimal speed, precision, lifting capacity and cost.
German-based Robo-Technology recently used
ANSYS Workbench tools to develop a six-axis robotic
system for ultrasonic testing of helicopter parts up to
six meters in length. The company reports that the
ability to analyze the design throughout the development process enabled them to verify that the rigidity
and vibration behavior of the system met customer
demands of rapid testing movements, high dynamic
precision and accurate synchronization among
multiple robots working together.
www.ansys.com
Similarly, Motoman Inc. in the United States used
ANSYS DesignSpace software in developing a robotic
overhead transport with a two-meter boom capable of
carrying a 50-kg payload. Simulation technology is
said to play a major role in the company’s product
development group, which used ANSYS DesignSpace
to create a boom with less mass so engineers could
increase the reach and payload of the equipment.
Insight into Complex Equipment Behavior
Simulation is a powerful tool for better understanding
the behavior of complex industrial machines. With this
insight, engineers can then more effectively optimize
designs and develop innovative concepts. The NonFerrous Metals Technology Group of Hatch Australia
uses advanced analysis tools such as CFD for design
evaluation, optimization and problem-solving in which
heat transfer, fluid flow, combustion and mass transfer
are critical issues. Hatch is a leading engineering
consulting firm specializing in scale-up of process
technology from prototype pilot systems to large
production systems.
In one project, researchers used ANSYS CFX
software in analyzing a multiphase grinding mill
that vigorously stirs incoming material together with
solid grinding media using a series of high-speed
rotating disks. The CFD analysis showed the complex
multiphase swirling flow through the mill’s intricate
geometry and the nature of media distribution,
secondary flows and wear characteristics of parts. In
this way, simulation has improved the understanding
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Volume 7, Issue 4 2006
9
of mill behavior for scale-up of the design and also has
generally enhanced mill operation.
Adding Revenue by Shortening the
Development Cycle
Computer simulation reduced time needed to develop
a new aggregate drying burner designed for use in
asphalt plants from the normal six to 12 months to
only 32 days. Manufactured by Astec Industries in the
United States, the burner is intended to remove
moisture from rock so it will bind properly to cement in
forming asphalt. Getting dryers to market as quickly as
possible necessitated development of the burner in
an extraordinarily short time, yet there was barely
time to build a single prototype.
The Astec design team used FLUENT CFD technology, recently added to the ANSYS suite of software
solutions, to readily evaluate numerous virtual prototypes and quickly iterate to an optimized design. The
primary concern was determining the best way of
injecting fuel to obtain an optimal gas mixture. CFD
saved considerable time by determining the flow and
chemical concentrations early in design, providing far
more information than ever would have been possible
with physical experiments. In only two weeks, a
working prototype was built; within a month, the
design was optimized to meet stringent emission
regulations. In this way, simulation drastically
reduced time-to-market, thus providing up to a year
of additional revenues while substantially reducing
engineering costs.
In developing an asphalt plant burner, CFD simulation shows
velocity contours and pathlines indicating flow distribution around
the fanwheel (top). Diffusive mixing of methane is indicated by
pathlines around the gas injection pipe assembly (bottom).
Images courtesy Astec Industries.
More Time for Better Quality and
Greater Innovation
ANSYS structural analysis software is a core tool
for the state-of-the-art development facility at the
headquarters of Husky Injection Molding Systems Ltd.
in Canada. The company designs and manufactures
the plastics industry’s most comprehensive range of
injection molding equipment, including machines,
molds, hot runners and robots.
In developing these large injection molding
machines, engineers face demanding design
challenges. Machine weight must be minimized to
keep manufacturing and transportation costs low.
Operating speeds must be fast enough for required
throughput of manufactured plastic parts. Reliability
and precision must be maintained to provide
satisfactory service with minimal downtime. Efficiency
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Volume 7, Issue 4 2006
Industry Spotlight
10
is a requirement to keep energy consumption low and
thus minimize operating costs.
Engineers at Husky met these challenges with
ANSYS Workbench and ANSYS DesignSpace tools.
The integrated solutions provided efficient contact
representation for complex nonlinear assembly
analysis, additional pre-analysis in construction
and the benefit of common simulation methods in
the various types of analyses. Engineers report
that analyses formerly taking a week now can be
completed in just half a day. This level of increased
analysis efficiency is said to enable development
teams to achieve better machine quality and greater
innovation in products such as the company’s new
Reflex platens.
New Rotodynamics Capability Increases
Analysis Productivity
Design analysis of parts and assemblies in the
industrial machinery industry involves complex
computer-aided design (CAD) assemblies. To
accurately handle these geometries in the design
process, ANSYS offers close connection with CAD
to access geometry and material parameters; it also
allows quick turn-around while preparing geometry for
analysis. Geometry creation and editing tools allow
geometry manipulation for physics-based meshing
and analysis.
U.S.-based Trane, a business of American
Standard, Inc. and a leading worldwide supplier of
HVAC (heating, ventilating and air conditioning), uses
ANSYS software to design rotating equipment in
industrial chillers and air conditioning equipment using
the new rotordynamics capability. The ability to import
full 3-D CAD models into ANSYS Workbench allows
the user to analyze accurate 3-D models instead of
creating simplified 1-D representation of the geometry.
Productivity tools such as automatic contact detection
allow for easy problem setup and more time spent on
engineering design decisions.
To survive in the global economy of the third
millennium, manufacturers need to be inventive in
terms of factory equipment and raw materials, as well
as with the processes they develop. Using simulationdriven design efforts can bring value and innovation to
a wide range of product development applications. ■
The author wishes to thank development, technical support
and marketing personnel at ANSYS, Inc. for their efforts and
contributions to this article.
Trane uses ANSYS geometry (top), meshing (middle) and dynamics
(bottom) solutions to design HVAC systems and comprehensive facility
solutions for factories and other large commercial and industrials.
Images courtesy Trane, a business of American Standard, Inc.
www.ansys.com
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Volume 7, Issue 4 2006
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Image courtesy
Sheffield University.
ANSYS, Inc. Welcomes
Fluent Inc.
ANSYS broadens its opportunities to provide leading-edge
engineering solutions with the acquisition of Fluent Inc.
By Chris Reid
Vice President, Marketing
ANSYS, Inc.
On May 1, 2006, ANSYS, Inc. announced the completion of the acquisition of Fluent Inc., headquartered in
Lebanon, New Hampshire. Fluent is a global provider
of computer-aided engineering (CAE) products that
utilize computational fluid dynamics (CFD) principles
and techniques to enable engineers and designers to
simulate fluid flow, heat and mass transfer, and related
phenomena involving turbulent, reacting and multiphase flow. This acquisition reaffirmed the ANSYS
commitment to providing the open interface and
flexible simulation solutions that customers require.
What follows is some background information
to help you get better acquainted with the newest
member of the ANSYS family.
History of Fluent Inc.
In 1982, when CFD was primarily of interest to
academic specialists, engineers at Creare, Inc., a New
Hampshire consulting company, collaborated with
researchers at Sheffield University in Sheffield, UK, to
develop an interactive, easy-to-use CFD software
product for engineers. Called FLUENT, the first version
of this software was launched in October 1983. The
product was so successful that, in 1990, the FLUENT
group at Creare split from its parent company, moved
to a new location and formed Fluent Inc.
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Rapid expansion of Fluent’s software business
ensued, and, in May 1996, Fluent acquired Fluid
Dynamics International, the developer of the
general-purpose CFD software FIDAP. In 1997, Fluent
acquired Polyflow S.A., the developer of POLYFLOW,
a specialty CFD software product for the analysis of
materials such as polymers, plastics, food and rubber.
Since its inception, Fluent has continued to
innovate and grow by offering superior CFD software
and services to companies around the world.
Industry-Leading Technology
The broad physical modeling capabilities of FLUENT
technology have been applied to industrial applications ranging from air flow over an aircraft wing to
combustion in a furnace, from bubble columns to
glass production, from blood flow to semiconductor
manufacturing, from clean room design to wastewater
treatment plants. The ability of the software to model
reacting flows, aeroacoustics, turbulence, moving
meshes and multiphase systems has served to broaden
its reach. Today, thousands of companies throughout
the world benefit from using FLUENT software.
The suite of Fluent CFD products includes
FLUENT, FIDAP and POLYFLOW for CFD analysis;
FloWizard, a rapid flow modeling tool that allows
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Volume 7, Issue 4 2006
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Engineers at Wenger Manufacturing gained better insight into
the operation of a vertical cascade dryer (used to manufacture
pet food) by utilizing CFD. The consulting team at Fluent was
able to provide Wenger with an understanding of the existing
dryer in order to improve their ability to market, specify, apply
and service it. Improved dryers allow food processors to meet
guaranteed levels of product components, decrease costs and
avoid recycling of fine particles that may detract from product
appearance and present a fire hazard. Detailed airflow and
pressure distribution in various sections of the dryer would be
impossible to obtain through physical testing and measurement — but were possible to simulate using FLUENT software.
Image courtesy Wenger Mfg.
design and process engineers to quickly and
accurately validate their designs much earlier in the
product development cycle; FLUENT for CATIA V5,
which integrates Fluent’s rapid flow modeling
technology into the CATIA V5 product lifecycle
management (PLM) process; and FlowLab, a studentfriendly tool that uses the power of flow visualization
through CFD to teach basic fluid mechanics principles
in the engineering classroom. Fluent’s products also
include the preprocessors GAMBIT, TGrid and
G/Turbo. Application-focused products include Icepak
to optimize thermal management of electronics
designs; Airpak for modeling airflow, heat transfer,
contaminant transport and thermal comfort for the
built environment; and MixSim for the simulation of
stirred tanks.
Fluent always has taken pride in understanding
customers’ strategic goals and helping them come
to fruition through both software and services.
The complete array of services available addresses
the specific needs of organizations and supports
those organizations in implementing advanced
technology solutions. Services include consulting,
training and technical support.
Extensive Simulation Community
With the acquisition of Fluent Inc., ANSYS is pleased
to welcome Fluent software users to the world’s
www.ansys.com
largest simulation community. As a supplier to 94 of
the FORTUNE 100, ANSYS serves a wide range of
industries. They all have benefited from using ANSYS
software products and services — which continue to
expand, both with the addition of new technologies
developed via innovative research and development
and by acquisition, such as in the case of Fluent.
ANSYS now has one of the broadest ranges of
CFD simulation technologies in the world. ANSYS
believes that success relies on ensuring customers’
satisfaction. As such, in addition to focusing on
investment in product development, the company will
continue to provide the best possible service and
support through technical centers of excellence
around the world.
The addition of Fluent products to the ANSYS
portfolio significantly enhances the combined company’s
ability to provide world-leading simulation capabilities
to customers, consistent with the ANSYS vision
and strategy.
Broad and Integrated Solutions
ANSYS continues to concentrate on providing
customers with best-in-class CAE tools integrated in a
flexible manner that will enable easy and rapid analysis
and optimization of engineering designs.
Clearly, there is now the opportunity for tighter
linkages between ANSYS products, such as ANSYS
In this example, FLUENT software is used to optimize
the cooling package for a line of tractors. The cooling fan
characteristics, along with the placement of underhood
modules, are varied to achieve optimum performance.
Courtesy Case New Holland.
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Volume 7, Issue 4 2006
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CFD is becoming critical to the furnace design process, particularly as environmental regulations become more stringent. To help meet
these regulations, John Zink Company selected FLUENT software to assist in modeling flames for a vertical cylindrical furnace used in
an oil refinery. By using FLUENT, engineers were able to improve fuel mixing in order to decrease NOx production and maintain flame
height within the desired parameters. CFD modeling provided a proposed solution (right) to reduce burner interactions that had caused
increased flame height (left).
Image courtesy John Zink Co.
Mechanical or ANSYS Multiphysics, and Fluent
products, as the company has done already with
ANSYS CFX. The benefits of this strategy to
customers and the engineering simulation industry
have been real and measurable in terms of increased
innovation, greater productivity and lower costs.
ANSYS, Inc. fully expects to extend the same benefit
to today’s Fluent user community.
With the addition of more than 700 new
employees from Fluent and its subsidiaries, the
combined team with many years of simulation
experience, deep industry expertise and world-class
engineering talent will deliver even more exciting
advances in integrated CAE. To support the ability
to provide industry-leading advancements, ANSYS will
continue its focus on innovation and target approximately
20 percent of revenue to be spent on R&D.
Moving Forward
ANSYS and Fluent always have had much in
common. Now, the goals each company had for
the future are shared, and progress toward
these goals can be accelerated and fulfilled to the
benefit of customers. As in the past, ANSYS will
maintain a strong commitment to employees, partners
and customers as well as to the advancement of
technology through innovation. ■
Some of the world’s greatest soccer goalkeepers have been
beaten by unusual swerving balls that move left then right
before hitting the back of the net, even though they have little
or no spin applied to them. A team of researchers led by
Dr. Matt Carré at the Department of Mechanical Engineering,
University of Sheffield used FLUENT to demonstrate that the
shape, surface and asymmetry of the ball, as well as its initial
orientation, have a profound effect on how the ball moves
through the air after it is kicked. The image shows high-speed
airflow pathlines colored by local velocity over the Adidas®
Teamgeist 2006 soccer ball.
Image courtesy Sheffield University.
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Volume 7, Issue 4 2006
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The new sliding mesh capability in FLUENT 6.3
allows for many sliding interfaces within a
single simulation. In the case of the V22
Osprey, the rotating propellers gradually tilt
as the craft lands on a platform, changing
the propulsion from forward to hover mode.
FLUENT 6.3: Major Advances
in CFD Simulation
The latest addition to the ANSYS family features new solver,
modeling and other options — resulting in greater speed and flexibility.
By Christine Wolfe, FLUENT 6 Product Manager, Fluent Inc.
Nicole Diana, Product Planning Manager, Fluent Inc.
The current version of FLUENT software continues to
evolve, allowing difficult engineering problems to be
solved faster and with greater flexibility than
ever before. The upcoming release of FLUENT 6.3
offers innovative technology for addressing a broad
range of applications. In all, there are more than 100
new features that enhance core numerics and physical
modeling capabilities in areas such as moving
mesh, multiphase flow, combustion, reacting flow
and radiation.
New Solver Options
In FLUENT 6.3, a pressure-based coupled solver joins
the existing solver options. The new solver can
improve solution efficiency as well as convergence and
robustness for many cases. With this solver scheme,
the pressure and velocity equations are solved in a fully
coupled manner, while the other equations are solved
sequentially. It is particularly beneficial for “stiff” problems and for solving problems on unusually skewed
and stretched meshes.
In addition, existing FLUENT solvers have been
enhanced to offer improved robustness, accuracy
and efficiency. For example, strong shocks can be
captured more effectively with the density-based
solver, and transient simulations can be run more
efficiently with the pressure-based solver. Furthermore,
a new diagnostic case check algorithm can be used to
assess case settings and offer recommendations to
ensure that commonly accepted best practices are
being used.
www.ansys.com
Polyhedral meshes are being introduced in
FLUENT 6.3. These meshes allow the flexibility of an
unstructured mesh to be applied to a complex
geometry without the overhead associated with a
large tetrahedral mesh. The polyhedral meshes are
created using automatic cell agglomeration to
combine tetrahedral cells into polyhedral ones. This
can reduce the overall cell count by a factor of 3 to 5.
The automatic nature of these mesh agglomeration
techniques saves the user time and, since the polyhedral mesh contains as few as one-fifth the number
of cells in the original tetrahedral mesh, convergence
is faster.
In support of FLUENT software’s ongoing
commitment to parallel processing, numerous
improvements to parallel efficiency and flexibility have
In FLUENT 6.3, a discrete phase
of particles, droplets or bubbles
can be launched from a surface
at normal angles, as is shown
for a Rushton impeller in a
stirred tank.
ANSYS Solutions
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Volume 7, Issue 4 2006
Nylon is injected into a mold in this simulation of the production of a plastic
gear part. The plastic has non-Newtonian rheology, and the ratio of the nylon to
air viscosities is very large. To address this complex free surface flow, a new
interface tracking scheme in FLUENT 6.3 is used.
been implemented along with speed improvements for
reading and writing case and data files. High-performance computing also benefits from a 64-bit Windows
version of FLUENT 6.3.
New Modeling Options
New models and extensions to existing models add to
the technology’s capabilities in the areas of moving
mesh, reacting flow, multiphase flow and radiation.
FLUENT software’s industry-leading dynamic
mesh capability for modeling moving objects — such
as pistons and valves in IC engines, store, separation
and impellers in baffled mixing tanks — has been
enhanced. In FLUENT 6.3, the dynamic mesh
capability can be applied to a series of related steadystate simulations, making them easier for users to set
up and perform. For example, a control valve can be
simulated with a range of open positions by building
only one mesh and having FLUENT software rebuild
the mesh for each new position. Other improvements
make problem setup and user-defined mesh motion
even more straightforward and efficient.
In some cases, the motion of objects can be
captured by using regions of mesh that slide along
a common interface. This technique is useful for
modeling two trains passing in a tunnel, for example.
FLUENT 6.3 now is able to model more complex
object motion by allowing for multiple sliding mesh
regions on one side of an interface to be paired with
multiple sliding regions on the opposite side.
Reacting flow simulations benefit from new slow
chemistry and micromixing models, useful for liquid
reactions and certain combustion applications. A
larger number of chemical species and reactions can
be handled in the non-premixed and partially premixed
combustion models. Emissions modeling is more
comprehensive through the addition of SOx prediction
and the selective noncatalytic reduction of NOx
through urea injection. Expanded in-cylinder combustion capabilities include the ability to model ignition
delay in stratified engines.
Multiphase modeling continues to be an area
of focus for FLUENT 6 development, and major
improvements can be found in the accuracy of
transient multiphase solutions. For the Eulerian multiphase model, enhancements extend the regimes for
which this model can be applied. For example, both
compressible gas and liquid phases can be present,
and the mixing plane model can be used, simplifying
the solution of multiphase flows in pumps. For free
surface flows simulated using the volume of fluid (VOF)
model, a new interface tracking scheme is available
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that improves solution stability when the viscosity ratio
between the phases is high. FLUENT 6.3 technology
also allows a user-defined function (UDF) to be utilized
to specify the wall contact angle, allowing a dynamic
value to be calculated from the local flow field. This
feature is of primary importance for capillary-driven
flows in which surface tension is important.
For simulations involving surface-to-surface
radiation, extensions to the existing model make the
problem definition easier, and increase the solution
efficiency and range of applicability. For example, this
technique now can be used for 2-D axisymmetric
cases, and the participating boundaries can be
specified more easily in the graphical user interface.
Add-On Modules and Third-Party Tools
Several capabilities can be added to FLUENT software
through add-on modules. A population balance
module is new with FLUENT 6.3. This module makes
it possible to model multiphase flows with a particle
or droplet size distribution. Three approaches are
available that account for breakup and agglomeration
so that applications such as bubble columns and
crystallizers can be modeled. The proton-exchange
membrane (PEM) and solid-oxide fuel cell (SOFC)
modules have been enhanced in FLUENT 6.3.
For PEM fuel cells, transient simulations can be
performed and electrical conductivity can be obtained
from the FLUENT materials database. For the SOFC
module, the range of conditions that can be simulated
has increased.
Another improvement in FLUENT 6.3 is the ability
to work with third-party CAE packages. It is now
easier to import and export files to and from other
analysis tools (for fluid structure interaction, for
example) and postprocessing tools (such as EnSight
or Fieldview, for example).
Along with many other features, these highlights
make FLUENT 6.3 software a major step forward in
commercial CFD capability. ■
The ability to solve on polyhedral meshes is
new in FLUENT 6.3. Tetrahedral cells are
agglomerated to form polyhedra in the solver,
resulting in a reduced overall cell count that
requires less CPU time to reach convergence.
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Volume 7, Issue 4 2006
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16
Analyzing Composites
for Satellite Components
Researchers used ANSYS technology to study the behavior of a
composite housing for electronic circuits and quickly developed a
design nearly 30 percent lighter than a comparable aluminum structure.
By Harri Katajisto
R&D Engineer
Componeering Inc.
Helsinki, Finland
Scientific, observation and reconnaissance missions
often are performed by low-orbiting micro-satellites.
These systems are much smaller and more compact
than larger telecommunications satellites, so space
is severely limited and heat is more difficult to
dissipate from closely packed electronic components.
Traditionally, satellite electronics housings are made of
aluminum. This material is lightweight, has adequate
heat dissipation and provides good protection against
ambient spatial radiation.
In one recent study, the European Space Agency
(ESA) investigated the feasibility of fabricating these
housings of composites to determine if this type
of material systems could provide the same heat
dissipation as aluminum but with less mass. In this
study, Verhaert Design and Development in Belgium
Figure 1. The Proba 2 micro-satellite has instruments to
make solar observations and space weather measurements. The electronics housing from this micro-satellite
was used as a reference application in the ESA study.
Image courtesy Verhaert Design and Development.
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ANSYS Solutions
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Volume 7, Issue 4 2006
Figure 2. The housing with its back panel removed shows
composite laminate structures together with aluminum
wedge locks and mounting rails.
Photo courtesy LLS/HUT.
provided the reference application for the study: the
Advanced Data and Power Management System
(ADPMS) aluminum housing for the Proba 2 microsatellite in Figure 1. Analysis of the composite housing
was performed by Componeering Inc., which specializes
in simulation and design of high-performance composite structures. The Laboratory of Lightweight
Structures at Helsinki University of Technology
was responsible for the design, prototyping and
manufacturing of the housing, shown in Figure 2.
The Challenge of Designing with
Composites
Designing composite structures with sandwich-type
elements or layered solid laminates is very challenging
due to the anisotropic behavior of the material.
Moreover, the design depends on multiple variables
such as material selection, number of layers, layer
orientations and stacking sequence.
In the structure under investigation, performance
requirements for the composite housing were derived
from the requirements of the aluminum housing.
For example, the goal in radiation protection was
to provide shielding against spatial radiation in low
earth orbit comparable to the aluminum design with a
2mm wall thickness. This was achieved by embedding
tungsten foil inside the carbon fiber-reinforced
plastic (CFRP) laminate structure of the housing
external panels.
One important requirement was that mechanical
interfaces of the composite housing had to be
identical to the aluminum counterpart. Inside and
outside contours of the housing had to accommodate
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internal circuit boards and connectors as well as
external components of the satellite. These constraints
limited the composite design, in which smooth shapes
are preferable.
To provide thermal management comparable
to the aluminum housing, heat dissipation for the
composite structure was provided by layers of
plastic reinforced with K1100 pitch-based carbon
fibers. Combined with the plastic matrix as a ply
configuration, these fibers yield about four times
higher thermal conductivity in the direction of fibers
than typical aluminum alloys. Moreover, the natural
black color of CFRP provides high emissivity, and heat
is dissipated very efficiently from the surface. From a
structural standpoint, however, the K1100 fibers
exhibit very low failure strain and break easily when
bent on a small radius.
Compounding the design challenge, mismatches
in coefficients of thermal expansion (CTE) between the
composite housing and aluminum wedge locks and
satellite support structures cause deformations when
the structure is subjected to temperature change.
Because of these complexities, determining
thermal balance, structural integrity and resonant
frequencies of the housing using conventional analysis
methods can be an extremely cumbersome task.
Results would most likely have a high probability of
error due to simplifications that would not adequately
account for all design variables.
Advanced Tools for Simulation and Design
To meet these challenges, we performed a wide range
of analyses using ANSYS Mechanical software
throughout the project. During conceptual design,
laminate through-the-thickness direction behavior was
studied with a solid thermal model using SOLID70
elements as shown in Figure 3. (See next page.)
Analysis results demonstrated that single-layer
elements are adequately representative for thin
laminates in steady state, so only in-plane thermal
conduction capability of the SHELL131 element was
used. The effective conductivities of the laminate were
verified easily with capabilities of SHELL131 and
simple test models. Mechanical interfaces and
adhesively bonded joints were modeled using
thermal LINK33 elements, with contact resistance
depending on joint materials, surface roughness and
contact pressure. Input data definition for thermal links
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Volume 7, Issue 4 2006
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18
Figure 3. Representative 3-D model illustrates temperature
variation in the laminate through-the-thickness direction (left)
and high thermal flux in the two K1100 layers located on
both surfaces (right).
was based on a literature study. Both conduction
and radiation heat transfer modes were considered.
The radiation effect was applied using the SURF151
element that was overlaid onto the SHELL131
element.
Thermal analysis of this type is readily performed
in ANSYS software, which provides the capability to
use nodal temperatures resolved from the thermal
model as an input for the structural model. The use of
this feature is very simple, since ANSYS internally
converts the thermal results file *.rth to equivalent
force and moment vectors in the structural model.
In this study, in-service temperature variations in
laminate structures were quite small, so thermal
bending was not an important factor. However, thermal
bending was found critical in some manufacturing test
trials in which laminate structures were bonded at high
temperature with aluminum wedge locks. For these
cases, SHELL181 has proved to give excellent results,
providing ease of controlling the laminate crosssection input data.
The wedge locks do not fully cover the hat
section in the depth direction, and ANSYS thermal
analysis revealed that part of the heat-dissipation
capacity was lost with K1100 layers oriented in the
longitudinal direction of the housing, as shown in
Figure 4. It was found that when K1100 layers were
oriented in ±30 degrees, the temperature distribution
was more homogenized, the peak temperature was
the same and, structurally, the lay-up was acceptable.
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The stiffness requirements of the housing
dictated the number of required structural M40J CFRP
layers. The orientation and stacking sequence of both
K1100 and M40J layers was based on the laminate
stiffness and CTE. CFRP structures have slightly
negative CTE in the fiber direction. Respectively, in
the perpendicular direction to the fibers, CTE is in
the magnitude of aluminum. The wedge locks were
adhesively bonded to the laminate structures
and acted like stiffeners. Due to this bonding
and orientation, the CTE of the laminate was an
important design parameter.
The laminate design was performed using
ESAComp software (www.esacomp.com), which is a
dedicated tool for preliminary and detailed analysis of
composite structures. ESAComp interfaces smoothly
with ANSYS software. Laminate lay-ups and material
data can be exported to ANSYS for composite solid
and shell elements. Moreover, FEA results from
ANSYS can be imported to ESAComp for detailed
post-processing. This capability was used, for example,
in studying the criticality of the laminate interlaminar
shear (ILS) stresses, which became high close to the
inserts that were used to attach different panels.
Creating simulation models was facilitated using
ANSYS Parametric Design Language (APDL), which
could be linked to ESAComp for optimizing the
design. With APDL, an external software such as
ESAComp can be readily linked to the design cycle,
thus allowing simulation to effectively guide the
development process toward the best design.
After completion of the thermal analysis with
ANSYS software and laminate design with ESAComp,
ANSYS Mechanical was used for structural analysis of
the housing, including a modal analysis for natural
Figure 4. ANSYS thermal analysis of the composite hat section
revealed that heat-dissipation capacity varied according to
the orientation of the K1100 layers of the laminate.
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Volume 7, Issue 4 2006
Figure 5. The same ANSYS model was used for both structural
and thermal analysis in determining characteristics such as
the thermal balance of the laminate structures and mode
shapes of the system.
frequencies up to 800 Hz. Modal analysis results
together with the random vibration input specification
defined the acceleration levels for the subsequent
failure analysis. The design was predicted to withstand
load levels multiplied by factor of safety of two,
which is a typical value for composite materials in
space applications.
In the ANSYS model for these structural studies,
the quadratic composite SHELL99 element was
used for meshing the laminate structures. SHELL99 is
applicable to thin laminates, but it contains transverse
shear deformations capability as well. Bolted joints
and inserts were modeled using the BEAM4 element
in order to be able to extract laminate bearing stresses
and insert pull-out forces.
Impact and Benefits of the Solution
Thermal tests performed in the vacuum chamber at
the European Space Research and Technology Centre
(ESTEC) in the Netherlands corresponding to the
worst hot temperature condition of the equipment
confirmed that simulation accurately predicted
the satisfactory heat-dissipation capacity of the
composite housing.
Using an electromagnetic shaker, sine and
random vibration tests of a breadboard model were
conducted at the Royal Military Academy in Brussels,
Belgium. The composite housing was found stiffer
than its aluminum counterpart, and overall behavior of
the system was as predicted with simulations.
www.ansys.com
In this project, ANSYS software worked smoothly
in exchanging data with ESAComp. Time was saved in
generating simulation models by importing required
data directly from ESAComp into ANSYS, as well as
taking advantage of automated features of ANSYS
contact elements and power of APDL for parameterization. Considerable time also was saved through the
ability to use the same ANSYS model for both
structural and thermal analyses, as shown in Figure 5.
In the course of the project, details of the composite
structure were studied with simulation before going
through the time and expense of building physical
prototype breadboard models. In this way, the
modified structure could be analyzed and feedback
provided almost instantly to the design team.
The ability of ANSYS software to work well with
ESAComp, to provide a robust parametric model
representing all the different components and to
reliably perform both structural and thermal analyses
was key to the speed and accuracy in successfully
completing the study. With the help of this level of
advanced analysis, the behavior of the structure could
be properly understood, the design of the composite
housing was optimized to provide a mass saving of
29 percent over a comparable aluminum housing and
the project was completed in only 18 months from the
kick-off meeting to the final presentation of results. ■
Refer to the following papers for more information on
this project:
Katajisto, H. et al., “Structural and Thermal Analysis of
Carbon Composite Electronics Housing for a Satellite,”
Conference Proceedings of the 1st NAFEMS Nordic
Seminar “Component and System Analysis Using Numerical
Simulation Techniques — FEA, CFD, MBS,” Gothenburg,
November 23-24, 2005.
Brander, T. et al., “CFRP Electronics Housing for a Satellite,”
Proceedings of European Conference on Spacecraft
Structures, Materials and Mechanical Testing, Noordwijk,
May 10-12, 2005.
Jussila, J. et al., “Manufacture and Assembly of CFRP
Electronics Housing,” Proceedings of European Conference
on Spacecraft Structures, Materials and Mechanical Testing,
Noordwijk, May 10-12, 2005.
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Volume 7, Issue 4 2006
19
Visualization of the turbine velocity vectors
at the blade mid-span location
20
CFD Simulation Brings Electrical
Power to Rural Areas
ANSYS CFX software improves the design and efficiency of a small
hydro-generator for use in remote areas of developing countries.
By Robert Simpson, Ph.D.
Nottingham Trent University, UK
In developing countries, many remote rural communities
do not have access to electricity due to the large
expenses associated with extension of the national
grid. Where these communities have access to a
suitable site, small hydroelectric schemes are found to
be a cost-effective and sustainable means of providing
electricity. The Micro Hydro Research Centre at
Nottingham Trent University has been carrying
out research into small-scale standardized hydrogenerator units that are directly affordable for villagers
in developing countries.
Low-head hydro sites (2 to 10m) offer the
potential for providing electricity to many communities,
but progress has been hampered by the lack of an
appropriate turbine design. A research project has
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been undertaken in collaboration with Practical Action
Peru (formerly known as Intermediate Technology
Development Group) to develop a standard design
procedure for the cost-effective local manufacture
of pico-propeller turbines with good performance
and reliability. Pico-hydro is the smallest classification
of power output with a maximum output of 5kW.
Fixed geometry propeller turbines are one of the
most cost-effective turbine options for low-head
pico-hydropower.
The first objective of the project was to design
a simplified prototype turbine based on current
knowledge and to have it manufactured and installed
at a field site in Peru. Stage two involved analyzing
the turbine using computational fluid dynamics (CFD)
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Volume 7, Issue 4 2006
to improve the design and efficiency. Using CFD
provides the flexibility to make design changes,
investigate scale effects and vary the hydrological
conditions (head and flow rate) without the need and
expense of creating a prototype for each test case.
ANSYS CFX software was used for all aspects
of the CFD study because of its good track record
with turbomachinery analysis and because it is
part of an integrated system of software, which
includes CFX-BladeGen (now ANSYS BladeModeler)
and ANSYS TurboGrid for design and analysis of
bladed geometry.
21
Prototype Turbine in Peru
The prototype turbine for the project is located on a
small farm in the northern highlands of Peru. Currently,
the turbine is producing electricity for the owner’s
farmhouse located several hundred meters away, and
the horizontal shaft layout was designed to facilitate
easy connection to existing mechanical equipment
used by the farmer to produce feed for several chicken
farms. Water for the turbine is diverted into a concrete
channel from an existing irrigation channel that runs
across the plot of land.
The spiral casing has a simplified design with
a tapered rectangular cross-section. The rotor
blades were manufactured using flat sheet metal
bent and twisted into the required shape. Preliminary
field testing of the turbine revealed several problems
during operation. Water was being emptied from
the forebay tank, resulting in a much lower head than
the available four meters, and the turbine was not
producing sufficient power to get the generator up
to operating voltage.
Simulation Helps Refine the Design
Simulations performed on the original rotor geometry
showed that the maximum turbine efficiency was
predicted to be approximately 55 percent at 600 rpm
with a flow rate of 284 liters per second (l/s). However,
available flow rate at the site was measured to be in
the range of 180–220 l/s, which was not enough flow
for the turbine to operate efficiently. From this
preliminary study, it was concluded that the blade
angles for the original rotor were incorrect. A new rotor
with flatter blades and a higher solidity ratio was
designed using conventional theoretical methods. The
new rotor geometry was analyzed using ANSYS CFX
software, and the results predicted a significant reduction in the flow rate required to obtain the same power
output. In addition, the power curve demonstrated an
improved performance over the speed range with a
predicted best efficiency for the new rotor of 80
percent at 800 rpm.
www.ansys.com
This project was undertaken to provide power to a farmhouse
in rural Peru that is used to grind feed for several chicken
farms owned by the farmer.
The civil works required for power generation consisted of a
concrete channel, silt basin, forebay tank and the powerhouse.
The turbine drives an induction motor as generator (IMAG)
with controller. The radiator-type ballast loads can be seen
glowing red in the picture (upper left).
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Volume 7, Issue 4 2006
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Preliminary CFD simulations were used to compare the
original and redesigned rotor geometry. A total pressure
boundary condition was used for the inlet to simulate a
constant head of four meters.
The new rotor was fabricated by a local manufacturer in Peru, and field test data was obtained.
A revised and more accurate CFD model also was
created, which took into account parameters and
geometry changes that were not included in the
preliminary simulations.
The revised CFD simulations had reasonable
agreement with the field test results for the power
output in the low-speed range. However, in the
high-speed range (above 1200 rpm), the results tend
to overpredict the power output when compared
to the field tests. The flow rate through the turbine
also is underpredicted by the CFD simulations by
approximately 10 precent. Further investigation is
currently under way to determine the effect of changes
to the ANSYS CFX model, including roughness
effects, leakage losses through the hydrodynamic
seal and cavitation modeling.
The revised CFD simulations for the redesigned rotor show
reasonable agreement with the field tests for power output.
The new rotor was manufactured locally using flat sheet
metal bent and twisted into shape and welded to the hub.
Ongoing Research
ANSYS CFX software has been used successfully to
analyze and identify an operational problem with the
original prototype turbine for the project. Furthermore,
the software has proved to be a valuable design tool in
the process of developing and analyzing possible new
rotor geometries for the turbine. At the time of writing,
the turbine was producing approximately 4kW of electrical
power on site at a turbine efficiency of 65 percent.
Ongoing research aims to further improve the turbine
design and complement the existing CFD and
field-test results with detailed laboratory testing. ■
This project is funded by a research grant awarded by
the Leverhulme Trust to Arthur Williams, Ph.D. (principal
investigator) and Shirley Ashforth-Frost, Ph.D., Nottingham
Trent University, UK.
For further information, contact Robert Simpson
([email protected]) or Arthur Williams
([email protected]) of Nottingham Trent University.
Visualization of the velocity vectors at the
Thelocation
fluid volume for the ANSYS CFX simulation was
blade mid-span
separated into four domains: the spiral casing, guide
vanes, rotor passage and draft tube.
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Volume 7, Issue 4 2006
Guest Commentary
Integrating CAD and CAE to
Enable Simulation-Driven Design
Lack of knowledge capture and re-use holds
many companies back from gaining the full
benefits of analysis.
The explosion of computational
capacity, now at rock bottom
prices, will turn engineering
simulation into an everyday
tool for all engineers and
designers across the full
product development process.
In such a paradigm shift, CAE
begins up front with conceptual
design, engineers perform
much of their own simulation
and analytical results drive
design decisions. Simulation
experts determine the right process, analysis assumptions and check-points to validate results — but do
not directly execute analysis work.
What’s holding us back from integrating CAD
and CAE to enable simulation-driven design?
Our Design/Simulation Council addresses these
challenges with a proposed standard framework
to integrate and optimize the divergent specialist
activities that fragment design and simulation. A core
problem relates to lack of knowledge capture and
re-use regarding simulation.
Some forward-thinking companies are making
significant headway in leveraging the knowledge of
expert specialists in their simulation-driven design
efforts. Several initiatives rely on an abstract model
representing analysis work that can be performed
across similar parts, at all stages of product development and across all analysis domains. The model
includes three main types of information:
■ Input for the early concept phase covering
performance requirements and functional
specifications
■ Company rules and practices, product
identification, context of the analysis and
engineering knowledge or constraints
that apply
■ Analysis-related information as a function
of part and product type that includes
the part or system definition, geometry,
assumptions, loads, boundary conditions
and materials data
www.ansys.com
By Don Brown, Chairman
Collaborative Product Development
Associates, U.S.A.
The abstract model is used as a basis for creating a
specific physical model for analysis. Mesh generation
and formatting then translate the physical model into an
analysis execution model for a particular solver.
Broad implementation of such approaches
involves a transformation for product development.
Considerable data management is required to store
expert knowledge and data models. CAE solutions
must be architected to leverage this knowledge. Most
important, organizational changes must meet the needs
for cross-functional collaboration to integrate design
and analysis.
Leading-edge companies, including Airbus,
Visteon, Whirlpool and John Deere, successfully utilize
such an approach. At Visteon, the abstract model drives
all automotive air-handling systems across both
CAD and CAE. The abstract model is defined by 15
components, 12 classes and 40 attributes. Airbus
is standardizing structural analysis across all sites and
disciplines by automatically generating data needed for
a particular analysis code from a CAE data model that
contains analysis abstract models, rules, relationships
and other information. For example, the shape and
dimension of each rib in a wing can be defined from a
set of design rules and constraints, and models may
apply to all frames of all aircraft based on particular
plane geometry, loading conditions and materials.
Today, as in the past, simulation technology too
often is used only as a forensic tool for post-mortem
checks, validation and troubleshooting after the fact,
when the worst of the damage already has been done.
Too many critical product development decisions are
made based on assumptions and guesses rather than
on engineering analysis, even though the tools are
readily available. Simulation should be applied up front
to avoid problems in the first place. ■
Collaborative Product Development Associates
(www.cpd-associates.com) provides in-depth information for assessing technology, business goals and
implementation road maps for engineering and
manufacturing. The firm hosts a variety of events and
engages in programs for critical analysis of decision
trade-offs regarding design creation and validation,
design/simulation council, PLM integration/product
definition and product value management.
ANSYS Solutions
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Volume 7, Issue 4 2006
23
Simulation at Work
24
From the collection of
Jean-Pierre Lauwers.
CFD Simulation Recreates
Aviation History
Researchers used ANSYS CFX software to study the 1906 flight
of Alberto Santos-Dumont’s wood and silk aircraft, credited as
the first officially recognized heavier-than-air flight in Europe.
By Leonardo O. Bitencourt, Aeronautical Engineering, ESSS, Florianópolis, Brazil
Ramon Morais de Freitas, Instituto Nacional de Pesquisas Espaciais
Grégori Pogorzelski, Aeronautical Engineering, Instituto Tecnológico de Aeronautica
João L. F. Azevedo, Senior Researcher, Instituto de Aeronáutica e Espaço
A native of Brazil, Alberto Santos-Dumont was a
genius obsessed with the concept of flight. A hundred
years ago, he designed and built a plane from pine
and bamboo poles covered with Japanese silk in
a complex biplane, boxkite-like configuration. For
flight testing, he attached the aircraft to his latest
dirigible, the Number 14, and the plane became
known thereafter as the 14-Bis.
On October 23, 1906, at the Bagatelli Field in
Paris, Santos-Dumont flew his aircraft 200 feet and
won the coveted Deutsch-Archdeacon Prize, which
was created to encourage the growth of aviation. The
flight was witnessed by officials from what would
become the Federation Aeronautique Internationale,
and Santos-Dumont was credited with making the first
heavier-than-air powered flight in Europe.
Aviation pioneer Alberto Santos-Dumont
From the collection of Jean-Pierre Lauwers.
www.ansys.com
ANSYS Solutions
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Volume 7, Issue 4 2006
25
Geometry of the 14-Bis
To commemorate this milestone in the history of
aviation, a group of students in Brazil, assisted by
Engineering Simulation and Scientific Software (ESSS,
the ANSYS distributor in South America), established
the CFD 14-Bis Project to celebrate the historic
occasion through advanced computational fluid
dynamics techniques. ANSYS CFX software was
chosen to analyze and understand airflow around
the plane’s surface.
A CAD model was developed using historic
pictures, plans and discussion. Due to the model’s
complex geometry, the students meshed surfaces
using hexahedral elements and represented volumes
with a tetra/prism mesh. ANSYS ICEM CFD software
was used to create both high-quality surface and
volumetric meshes.
Some conclusions can be drawn from the
ANSYS CFX results. In his first attempt, SantosDumont used 24 hp nominal power and failed. In the
second and successful attempt, he increased the
nominal power to 50 hp. By analyzing drag and lift as
well as engine thrust, the possible angle-of-attack and
flight speed values could be estimated: Approximately
five degrees and the range of 12 to 14 m/s are
the predicted flight conditions. These values are
higher than the speed of 11 m/s normally quoted
in describing the flight.
As this value is a ground-related speed, the
possible discrepancy could be due to the presence of
wind or ground effects during the centennial flight.
This last factor currently is being studied. Aspects
related to aircraft stability still are under investigation,
Lift dependence with flight velocity
www.ansys.com
Meshing the 14-Bis using ANSYS ICEM CFD software
but preliminary results indicate that the airplane was
stable even though small variations in the center-ofgravity position could make the airplane dangerously
approach unstable behavior. The simulation gave
researchers insight into the airflow and dynamics of
the plane as well as the genius and daring of the
aviation pioneer Alberto Santos-Dumont. Q
The authors wish to thank Professor Paulo Greco from Escola
de Engenharia de São Carlos, Universidade de São Paulo,
who provided the geometrical CAD model, and Marcus Reis
from ESSS, who provided support and licenses for all the
software used.
Flow visualization using streamlines
Qualitative analysis of velocity
ANSYS Solutions
|
Volume 7, Issue 4 2006
Simulation at Work
26
Weight-Optimized Design
of a Commercial Truck Front
Suspension Component
Engineers at Dana Corporation use topology optimization features
of ANSYS Mechanical software to reduce upper control arm weight
by 25 percent while maintaining required stiffness and strength.
Headquartered in Toledo, Ohio, Dana Corporation is
a leading supplier of parts and assemblies to the
automotive industry. The company designs and
manufactures a wide range of products for every
major vehicle producer in the world and has twice
received the Malcolm Baldrige National Quality
Award, which recognizes U.S. businesses that
demonstrate outstanding quality and performance.
Dana is focused on being an essential partner to
automotive, commercial and off-highway vehicle
companies, which collectively produce more than
60 million vehicles annually.
Dana’s Commercial Vehicle Systems Group
specializes in development of front-steer, rear-drive,
trailer and auxiliary axles; driveshafts; steering shafts;
suspensions; and related systems, modules and
services for the world’s commercial vehicle market.
Dating back to the company’s beginnings in 1904,
Dana products have helped drive history’s greatest
vehicles, from the Model T and World War II-era army
vehicles to London taxicabs, 18-wheel rigs, giant
earth-moving machines and cars on the NASCAR
racing circuit. Building on this foundation of
Designed by Dana Corporation for
commercial vehicles, the upper
control arm (highlighted) is a
critical component in vehicle
front suspension systems.
(Dana patents pending.)
www.ansys.com
ANSYS Solutions
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Volume 7, Issue 4 2006
27
Starting with an initial mesh (left), the ANSYS topology optimization routine automatically eliminates elements with stiffness below
a specified threshold (right). The result is an analysis model consisting only of the elements needed to maintain the required stiffness
with minimal material. (Patent-pending design)
experience, Dana continues its commitment to quality
and innovation in advancing the science of mobility for
the benefit of its broad global customer base.
guide engineers in completing the detailed design of
the weight-optimized part.
Key Part of Product Development
The Drive for Lighter Suspensions
Design of suspension systems and other assemblies
for heavy trucks is a formidable task due to heavy
loads, harsh environments and long-life requirements.
Historically, components tended to be over-designed
heavy structures to meet these reliability requirements.
But in today’s economy, the weight of commercial
trucks and its impact on vehicle cost, ride and fuel
economy are of significant concern for both truck
manufacturers and end users.
Lighter, well-designed suspensions provide
better ride quality, lower initial cost, increased fuel
economy and greater truck payloads. The challenge is
to design these parts with minimal material yet
still maintain adequate strength and stiffness — all
while meeting tight budgets and product launch
schedules that rule out building and testing numerous
hardware prototypes.
Working with Topology Optimization
Dana Commercial Vehicle engineers use topology
optimization features of ANSYS Mechanical software
to optimize component weight as part of the
product design process. The method begins by
determining loads from multibody simulation. Then an
initial rough solid model is constructed to fill the
maximum available space envelope allowed for the
component. Next, a finite-element mesh is developed,
and the ANSYS topology optimization routine
automatically eliminates elements with stiffness below
a specified threshold.
The result is an analysis model consisting of only
those elements needed to maintain the required stiffness
of the component with minimal material. This topologyoptimized model then is overlaid on the solid model to
www.ansys.com
Because weight reduction is a critical issue, this
optimization approach is used extensively with
considerable success at Dana. In the development of
an upper control arm for the front suspension of a
commercial truck, for example, engineers reduced
part weight by 25 percent while maintaining required
stiffness and strength.
The process was completed in less than a day,
compared to weeks otherwise needed for trial-anderror iterations on expensive physical prototypes.
Moreover, the optimization guided the design in a
direction that was not intuitively obvious and provided
engineers with greater understanding of component
behavior and stiffness transfer paths. The approach
has been standardized as a best practice in the group
and now is applied readily to optimize the weight of
most of Dana’s commercial truck components.
“The topological optimization capabilities of
ANSYS Mechanical software represent a key part
of our work in developing well-designed, lightweight
suspensions and other assemblies that meet the
stringent requirements of the commercial truck
industry,” explains Caner Demirdogen, senior principal
engineer at Dana Corporation Heavy Vehicle
Technologies and Systems. He notes that the
optimization approach implemented at Dana enables
engineers to take advantage of this technology in
reducing component weight much more quickly and
cost-effectively than trying to accomplish the same
goals with physical prototypes.
According to Demirdogen, “Such techniques
save considerable time and expense in developing
refined designs, give us tremendous insight into
component behavior and are a business requirement
for effectively designing tomorrow’s innovative
products in the competitive automotive industry.” ■
ANSYS Solutions
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Volume 7, Issue 4 2006
Simulation at Work
28
Developing Construction
Products with Better Fire
Performance
ANSYS tools provide models to accurately simulate
the complex physics of a building fire.
By Yulian Spasov, Ph.D., Corus Research Development and Technology, Rotherham, UK
and Yehuda Sinai, Ph.D., ANSYS Europe Ltd., Abingdon, UK
Fire performance is an extremely important aspect
of the innovative new building products being
developed for the construction market at Corus
Research Development and Technology (Corus
RD&T). Although standard furnace tests are conducted
to test compliance with current fire regulations, Corus
is taking this a step further by using simulation and
virtual testing to study the behavior of new
products under conditions that accurately represent
real building fires.
ANSYS CFX software was chosen as the CFD
tool in this virtual testing because of its reputation for
modeling combustion, radiation and buoyant flows,
and because Corus has a long tradition of using the
software. A first step toward developing reliable
simulation practices has been to validate the software
and modeling capabilities for specific situations
against available experimental data.
Experimental setup of dry wooden cribs in the fire
test compartment
www.ansys.com
Simulating Fire Tests
In 1993, the Fire Research Station of the Building
Research Establishment (BRE), in collaboration with
British Steel Technical, Swinden Laboratories (now
Corus RD&T) conducted nine fully developed
fire tests in a large compartment in the BRE
Cardington Laboratory. The photographic material and
experimental data presented here are extracted
from referenced documents. The fire load consisted
of 33 dry wooden cribs located on the floor of
the compartment. The ventilation opening was
obstructed by a column, and all cribs were set on
fire simultaneously. The experiment lasted three
hours, and the fire load was 20 kg/m2 of dry timber,
which was completely burned by the end of the
experiment. Temperature, velocity, radiation intensities
and major species concentration were measured at
selected locations. The weight of several cribs also
was monitored to estimate the actual crib burning rate.
By validating simulation results with an experimental fire, Corus
is confident in using ANSYS CFX to assist in improving the fire
performance of their products.
ANSYS Solutions
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Volume 7, Issue 4 2006
29
Simulation results for temperature
after 20 minutes (top) and 40
minutes (bottom)
Comparison with experimental data. Groups A and B (top left and right) thermocouples are
located near the ceiling at the back and middle of the compartment, while Group C (bottom
left and right) thermocouples are located inside the compartment, just behind the column.
For simulation, ANSYS DesignModeler, ANSYS
CFX-Mesh, ANSYS ICEM CFD Hexa and ANSYS CFX
10.0 products were used to build the geometry, fluid
mesh, solid mesh and simulation model, respectively.
The model takes advantage of eddy dissipation
combustion, Monte-Carlo gray radiation and the
SST turbulence models in ANSYS CFX software.
Conjugate heat transfer through the solid walls was
modeled using the generalized grid interface capability
for “gluing” together the unstructured fluid and
structured solid meshes. The computational domain
was extended to include a region outside the
compartment in order to minimize uncertainties in the
boundary conditions. The heat-release rate of each
crib was estimated by interpolation of the available
data for crib mass loss rate. An inflated mesh was
used in the near-wall region, and a finer mesh close to
the cribs. The fluid domain contained 150,000 nodes.
Predictions Agree with Experimental Data
for modeling of this type, and no adjustments have
been made to model parameters in order to obtain
better agreement with experimental data.
Building fires involve complex physics, and their
modeling requires accurate combustion, radiation
and turbulence models. The model within ANSYS
CFX software provided results that are accurate both
spatially and temporally. The intuitive nature of the
user interface, the embedded parametric capabilities
and the reliability of the available physical models
showed that ANSYS CFX software is an invaluable
tool that Corus can use to enhance the fire
performance of its products. Demonstrating the fire
performance of whole modular compartments built
with Corus products would be almost impossible to
do experimentally. Corus now is able to use the
ANSYS CFX model with confidence in situations in
which experimental data is not available or would be
too expensive and time-consuming to obtain by
means of physical models. ■
Temperature readings were taken in four groups of
locations. Comparison of the experimental data with
the predicted temperature shows a good agreement
for all groups for the duration of the simulation. The
present results are obtained only using best practices
References
B.R. Kirby, D.E. Wainman, L.N. Tomlinson, T.R. Kay, B.N.
Peacock, “Natural Fires in Large Scale Compartments,” a
British Steel Technical, Fire Research Station collaborative
project, 1994.
GME Cooke, “Tests to Determine the Behaviour of Fully
Developed Natural Fires in a Large Compartment,” Fire
Note 4, Building Research Establishment Ltd., Fire
Research Station, 1994.
www.ansys.com
ANSYS Solutions
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Volume 7, Issue 4 2006
Technology Update
30
The ANSYS Workbench environment allows for remote
solutions, letting a high-performance computer cluster
accelerate work transparently.
Bringing High-Performance
Computing to the Mainstream
Microsoft® Windows® Compute Cluster Server lets engineers and
analysts easily deploy, operate and manage workstation networks
that, until now, only IT professionals could set up.
By Kyril Faenov
Director, High Performance Computing Group
Microsoft Corporation, U.S.A.
Traditionally, high-performance computing (HPC)
has been used primarily by those lucky enough to
have massive endowments or grants, with access
to time on the supercomputer strictly rationed.
HPC generally meant a single, large, symmetric
multiprocessing (SMP) or vector supercomputer and
a budget to match.
www.ansys.com
Solving cutting-edge problems in science,
engineering and business has always demanded
capabilities beyond those of even the fastest workstations. Market pressures demand an accelerated
product development cycle and reduced time-toinsight. The use of commodity servers in compute
clusters now brings the power of supercomputing to
the workgroup or even desktop level.
ANSYS Solutions
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Volume 7, Issue 4 2006
In 1991, the cost of a 10 Gflop Cray supercomputer was $40 million; the computers were available
only in government labs, very large corporations or
academic research institutions. Today, that same 10
Gflop computing power is available in a four-node
compute cluster that can be bought off-the-shelf
for $4,000.
This proliferation of HPC has an enormous effect
on research and industry, making it possible to solve
problems that simply couldn’t be attempted before.
But it also presents challenges for both vendors and
consumers of HPC.
Challenges of Compute Clusters
When HPC was a single, large integrated supercomputer, the researcher didn’t have to worry about how
to deploy or manage the system — that was the job of
(usually several) dedicated information technology (IT)
professionals, with accompanying salaries and costs.
But as we move to compute clusters of commodity
servers, especially at the workgroup level, the
challenge is to provide an installation and management experience that doesn’t distract from the reason
for the cluster in the first place — without requiring
major IT resources that would change both the
economics and the immediacy of the interaction that
are driving this proliferation.
Another area of concern is security. When HPC
was a single supercomputer with carefully controlled
and allocated access, security was inherent in the
process: The system was physically isolated and had
no direct connection to corporate or other networks.
Each researcher’s job ran as a discrete, self-contained
batch job. Today’s HPC compute cluster often is
directly connected to the corporate network, and it is
shared across a diverse group of scientists, engineers
or analysts. Individual jobs may use only a portion of
the cluster at any one point, with other jobs running
simultaneously on other nodes in the cluster. Security
must be built in to the overall HPC environment to
protect the integrity of the cluster and the individual
jobs that run on it, as well as the corporate network on
which it resides.
Networking
Windows CCS 2003 has a four-step wizard that easily configures networking, deploys compute nodes without IT intervention
and manages cluster users.
www.ansys.com
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Volume 7, Issue 4 2006
31
Technology Update
32
Accelerating Work Transparently
The biggest benefit of an HPC compute cluster is
availability. Compute clusters consisting of commodity
servers have driven down the price per Gflop to the
level at which anyone can reasonably afford his
own HPC, and results are available faster and more
interactively. By taking advantage of applications
such as Distributed ANSYS, users can perform their
simulations quicker, get more people involved in the
simulation and reach product decisions faster.
Windows
The familiar Windows infrastructure is used by CCS 2003 in its
Microsoft Management Console for managing compute clusters.
ANSYS, Inc. has embraced the client–server
compute model in the ANSYS Workbench environment working with Distributed ANSYS. This enables
users to focus on performing simulations and allows
for remote solutions in the process, thereby letting
the advanced computing power of an HPC cluster
accelerate the work transparently.
Role of CCS 2003
Microsoft Windows Compute Cluster Server (CCS)
2003 provides a complete HPC cluster solution that:
■ Easily installs and deploys on
commodity servers
■ Is highly secure and robust
■ Easily integrates into existing data
environments
■ Leverages existing IT infrastructure
■ Scales from personal clusters to TOP500
clusters transparently
■ Brings HPC mainstream
®
®
By integrating directly with Microsoft Active
Directory ®, CCS 2003 leverages the existing IT
www.ansys.com
infrastructure, including Group Policy, to provide a
secure cluster environment. A simple four-step wizard
configures the networking, installs and configures the
remote installation service (RIS) to deploy compute
nodes from bare metal without IT intervention,
and manages the cluster’s users. Node deployment is
simple and painless, making it possible to create a
prototype solution on a small cluster and then scale it
up as needed.
CCS 2003 leverages the familiar Windows
management infrastructure as well, using Microsoft
Management Console (MMC) 3.0 for cluster
management while supporting Microsoft Operations
Manager (MOM) for monitoring and management,
and supporting Microsoft Systems Management
Server (SMS) for node updates.
CCS 2003 includes Microsoft Message Passing
Interface (MS-MPI), a secure and fully compatible
interface based on the Argonne National Laboratory
MPICH2 reference implementation to simplify
migration of existing code and integration with existing
HPC environments.
The new Job Scheduler supports both a full
command-line job management and a graphical
interface to simplify job submission and monitoring.
Job scheduling is part of the end-to-end security
of CCS 2003, which leverages Active Directory to
allow jobs to run with domain user credentials while
protecting those credentials from other jobs in
the queue.
Finally, CCS 2003 leverages Microsoft® Visual
Studio® 2005 to provide a familiar, integrated development environment that supports remote parallel
debugging on the cluster, allowing developers to
quickly test and debug their code. The rich Visual
Studio environment gives application developers the
tools and language choices they need.
Summary
The wide availability of compute clusters running
on commodity hardware is driving the proliferation
of high-performance computing. Microsoft Windows
Compute Cluster Server 2003, working with
applications such as Distributed ANSYS, provides
a high-performance computing platform that is
simple to deploy, operate and integrate with existing
infrastructure and tools. ■
For More Information
■
Microsoft HPC public Web site: www.microsoft.com/hpc
■
CCS 2003 community site: www.windowshpc.net/default.aspx
■
Windows Server x64 information: www.microsoft.com/x64
■
Windows Server System information: www.microsoft.com/wss
■
ANSYS Workbench information: www.ansys.com/products/
workbench.asp
■
Distributed ANSYS information:
www.ansys.com/products/parallel.asp
ANSYS Solutions
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Volume 7, Issue 4 2006
Tech File
Running Solutions
from Macros
33
These handy do-it-yourself files can
be real time-savers, both now and
for future projects.
By John Crawford
Consulting Analyst
It’s interesting how the way we
use ANSYS evolves as we
become more familiar with the
program. Most people begin by
using the menus for modeling
building and entering all the information needed to run
an analysis. As they gain experience, their use of
menus gradually is supplemented by entering commands
via the command line because it allows them to work
more quickly. With more familiarity, it’s an easy transition to use our knowledge of commands to write
macros and other input files in ANSYS Parametric
Design Language (APDL). Doing this taps into the real
power of ANSYS technology, whether it’s a macro for a
single specific application or one that can be used over
and over again.
One of the practices I’ve used over the years is to
run almost all my solutions with a macro or input file.
Macros and input files are exactly the same; they differ
only in how they are executed. A macro has a .mac
extension and can be executed by typing the macro
name in the command line. An input file contains the
same data but doesn’t have the .mac extension, so you
need to use the /INPUT command to tell ANSYS to
input the file and execute the commands that reside
within it.
or anyone else who might use the macro to rerun the
analysis at a later date.
The solution macro usually begins by resuming
the startup model; then it assigns values to parameters
that I want to use in the solution. When doing a model
analysis, I might define the frequency range and number
of frequencies to solve for as parameters and then use
these to control how the solution is performed. Or I
might use a parameter to tell ANSYS whether the
excitation for a PSD analysis is in the X, Y or Z direction.
The macro then uses these parameters as it
progresses through the application of loads and
solution settings and runs the solution for each load
step or substep. I always include comments in the
macro that explain what is being done and why.
Saving Time and Trouble
Writing solution macros may sound like a lot of
unnecessary extra work, but, for all but the simplest
solutions, it’s a tremendous productivity enhancer.
Here are just a few reasons why I use solution macros
in almost all my work:
■
It gives me a history of the loads and solution
steps to which I can refer when reviewing
results. Sometimes it’s difficult to remember
what loads or options I applied for a specific
load step or substep. Having them listed in a
macro removes all uncertainty regarding how
the solution was obtained.
■
Rather than starting ANSYS and resuming a
model, I can refer to the macro when someone
asks about the loads, the number of load
steps and other solution controls.
■
I can revisit an analysis later and rerun it in an
efficient and consistent manner. This is useful
when I need to run different loads and want to
duplicate the earlier solution as a starting
point.
Well Worth the Effort
Regardless of whether you use a macro or an input file
to run a solution, the benefits of working in this manner
make it worth the effort to write them. When doing an
analysis, I usually build the model and get everything
set up and ready to go, with the exception of most of
the loads and solution settings. I may include some of
the boundary conditions that I don’t expect to change
in the model, and I write a macro that contains other
loads and solution settings for each load step that will
be run. I usually define loads as parameters at the top
of the macro so they can be changed easily by myself
www.ansys.com
ANSYS Solutions
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Volume 7, Issue 4 2006
Tech File
34
■
I can easily vary solution settings (contact
element stiffness, convergence criteria,
substep size, etc.) to see what effect they
have on the analysis. In this manner, every
solution begins from the same starting point.
■
The macro can automatically calculate settings
that are unique to a specific solution. For
example, if I want to run a series of harmonic
analyses that vary from one frequency to
another, I can have the macro calculate alpha
and/or beta damping for each frequency.
■
It greatly reduces the possibility for errors
because I have a document that confirms
what I did to get the latest solution.
■
The macro can be listed in the appendix
of a report so readers know exactly what
was done.
■
The macro is easily shared with others who
wish to do similar solutions.
■
I can refer to the macro the next time I do
a similar type of solution and use it as a
foundation for future work.
element stiffness, number and duration of time steps,
and many other things that I needed to adjust to
ensure that the results were accurate and useful.
I’ve used solution macros for quite a while and
now have a substantial library of them. The next time
I want to do a power spectral density analysis, I have a
macro that I can refer to that will help me do it again.
Single point response spectrum? No problem. Transient dynamic analysis? I have macros that will help
me with that. Modal cyclic symmetry? I have a couple
of those macros. An axisymmetric transient heat transfer
solution that has the results applied to a 3-D structural
analysis? That’s in my library as well. Superelement
generation, use and expansion passes used in several
different types of analyses? I have all of these.
Whether I last ran a specific type of analysis last
week or five years ago doesn’t matter. I can review
the solution macro to retrieve the insight and
understanding I had at that time and quickly perform
the analysis that I want to run today. Because
ANSYS emphasizes upward compatibility in new
releases, the commands that worked in my earlier
analysis will work in my new analysis, too.
Benefits of a Macro Library
Leveraging Knowledge of ANSYS Tools
While all the above reasons make macros well worth
the time needed to write them, I think the last reason
benefits me the most. I have a library of solution
macros that cover a wide range of analyses done in
the past, and I frequently refer to these when tackling
similar projects. Here is an example.
Several years ago I did a transient analysis of a
pressure wave striking a panel to determine how the
stress wave propagates through the panel. This was a
fairly complicated analysis with very small time increments and several thousand load steps. A few years
later, I was asked to model a sphere impacting a
machined part to see how quickly the stress waves
moved through the part, what the alternating stresses
were, and how much reflection and damping were
taking place. Rather than re-invent the wheel, I pulled
up the macro from my earlier analysis to refresh my
memory of how I had previously solved this type of
problem, and I used it as the basis for the more
complicated analysis I was now beginning to work on.
This enabled me to work more quickly and avoid some
of the pitfalls I had worked through previously. Once I
had the new macro running, I could vary contact
Solution macros not only benefit me, but they also
help my customers. When I finish an analysis, I turn
over the model and the macros I used to run the
solution and perform the post-processing. This allows
the customer to duplicate the results at a later date or
to make changes to the loads and run a new solution.
By putting the loads at the top of the macro as
parameters and taking the time to thoroughly make
comments on what they are and how they are used,
the customer is able to change the parameters and
run a new solution without any special understanding
of APDL or ANSYS. This allows the customer to
leverage my knowledge of ANSYS to his benefit, so
he can run additional solutions without my being
directly involved.
I didn’t use solution macros on a regular basis
until I had been an ANSYS software user for quite
a while. But when I began writing and using them,
I discovered that it was a worthwhile investment in
time and effort that has paid off over and over again.
Maybe it will pay off for you as well. ■
www.ansys.com
ANSYS Solutions
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Volume 7, Issue 4 2006
Tips and Techniques
Working with
Coupled-Field Elements
35
PLANE223, SOLID226 and SOLID227 elements readily handle
multiphysics problems coupled via material response.
By Sheldon Imaoka / Technical Support Engineer / ANSYS, Inc.
When multiple physics problems are coupled
via material response, the physics need to be
solved simultaneously. This is a typical application
of the use of 22x coupled-field elements, which
have multiple degrees-of-freedom (DOF) and can
support piezoelectric, piezoresistive, thermoelastic
and thermoelectric materials.
Piezoelectricity
In piezoelectric materials, structural and electric fields
are coupled so that an applied voltage generates a
strain (and vice versa). Consequently, piezoelectric
ceramics are used as transducers to convert electrical
energy to a mechanical response or as sensors to convert mechanical energy to an electrical signal.
Mechanical stress {T} and strain {S} are related to
electric displacement {D} and electric field {E} via the
following constitutive equations:
Here, [sE ] is the compliance matrix evaluated at
constant electric field, [εT ] is the permittivity matrix
evaluated at constant stress and [d] is the piezoelectric
matrix relating strain to electric field.
The above relationship provides a basis for the
FEA piezoelectric matrix equations:
■
[KV ] is the (anisotropic) permittivity matrix with
permittivity values evaluated at constant strain
[εS ] or constant stress [εT ].
■
[Cu ] is the structural damping matrix, whereas
[CV ] represents dielectric losses.
Issues to consider: Since coupling is via the
coefficient matrix, a single iteration is required for
calculating coupled effects. Elements support nonlinear
static, modal, harmonic response and transient
analyses. The dielectric loss tangent tanδ can be input
via MP,LSST, which is part of [CV ]. Manufacturers’ data
typically have mechanical vectors in the form {x, y, z, yz,
xz, xy}, whereas ANSYS requires the input to be {x, y, z,
xy, yz, xz} — so the 4/5/6 terms need to be rearranged.
Piezoresistivity
For piezoresistive materials, an applied mechanical
stress or strain causes a change in the material’s
resistivity for use as sensors, for example, in which a
mechanical load affects the electrical signal.
The electrical resistivity [ ρ ] is related to stress
as follows:
in which [ ρ o] is the input (nominal) resistivity and [π] is
the piezoresistive stress matrix. Alternatively, the
piezoresistive strain matrix [m] may be input instead,
relating relative change in resistivity to strains.
The resulting matrix equations are:
Description of terms:
■
■
[KZ ] contains the piezoelectric effect, and the
piezoelectric constants can be input as either
[d] form (strain/electric field) or [e] form
(stress/electric field).
[K u ] contains (anisotropic) stiffness
coefficients, and these are either compliance
[sE ] or stiffness [cE ] coefficients.
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Description of terms:
■
[KV ] is the (orthotropic) electrical conductivity
matrix, which includes piezoresistive effects
as described above.
■
[Ku ] contains the (anisotropic) stiffness
coefficients.
ANSYS Solutions
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Volume 7, Issue 4 2006
Tips and Techniques
36
Issues to consider: Coupling is in the coefficient
matrix, but resistivity is based on calculated stress or
strain, so multiple iterations are required for calculating
coupled effects. Elements support nonlinear static and
full transient analyses. The change in resistivities can
be measured by a Wheatstone bridge configuration,
since this is how piezoresistive materials usually are
arranged. Input of permittivity allows for definition of
[CV ] to account for dielectric effects.
Thermoelectricity
In thermal–electric applications, two types of coupling
are present. Joule heating is an irreversible process
occurring when current flows through material with
electrical resistance, proportional to the current
squared and independent of the current direction:
Description of terms:
■
[KVT] is the Seebeck coefficient coupling matrix.
■
Joule heating {Qj} and the Peltier effect {Qp} are
included in the load vector.
The Thomson effect is not explicitly included
above, since it is accounted for when temperaturedependent Seebeck coefficients exist.
Issues to consider: Since Joule heating and
Peltier effect are accounted for by load-vector
coupling, thermal–electric analyses are iterative in
nature. Material behavior supports nonlinear static
and transient analyses. Absolute temperature needs
to be defined via TOFFST.
Thermoelasticity
Thermoelectricity consists of the reversible
Seebeck, Peltier and Thomson effects.
The Seebeck effect, defined by the coefficient α,
relates a temperature gradient with a potential
difference. An example application is MEMS power
generation converting heat to electrical power:
The Peltier effect, noted by π , is the reverse
condition in which a current causes a heat differential,
and the direction of the current determines whether
heat is removed or input. Typical examples are thermoelectric coolers:
The Thomson effect, described by the coefficient
µ, illustrates what occurs when a current flows through
a material with a temperature gradient:
Thermal–stress analyses are commonplace, in which
the temperature field is calculated and imposed as a
load vector on the structural model. However, the
piezocaloric effect (thermoelastic damping) also can be
modeled with 22x coupled-field elements for dynamic
applications. The constitutive relations are:
in which {α} is the coefficient of thermal expansion, S is
entropy density and To is the absolute temperature.
The combined system of equations is expressed in
matrix form:
Description of terms:
■
Seebeck, Peltier and Thomson coefficients
are related using absolute temperature To, so only
Seebeck coefficients need to be defined:
Thermal–electric equations are incorporated into
the FE matrices as follows:
[KuT ] is the thermoelastic stiffness matrix
(thermal expansion term) while [CTu] is the
thermoelastic damping matrix.
Issues to consider: The system of equations is
unsymmetric, although by having it matrix-coupled, the
effects are considered in a single iteration. Nonlinear
static, full transient or harmonic response analyses are
available. The piezocaloric term (also known as
thermoelastic damping because of the coupling of the
energy equation) is present only for dynamic (harmonic
or transient) analyses and does not act like structural or
viscous damping by always lowering the resonant
frequencies. Coefficient of thermal expansion provides
the coupling response for both [KuT ] and [CuT ] terms.
A temperature offset via TOFFST is required, with
the reference temperature designating strain-free
temperature. ■
Contact the author at [email protected] for the
entire paper from which this article was excerpted.
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