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August 18, 2006

Appearing on a Screen Near You:

by Bob Cramblitt

[This article appeared in ANSYS Solutions Volume 7 Issue 3. For more information on ANSYS software, visit www.ansys.com.]

NASA used it to provide insight into complex flow physics for Discovery's redesigned external fuel tank, to interpret flight and wind-tunnel data, and to design tests with smaller-scale models.

CRAFT Tech uses it to study terabyte-sized fluid dynamic and combustive problems associated with weapons delivery systems for supersonic fighter jets.

Researchers at the National Energy Technology Laboratory and Pittsburgh Supercomputing Center use it to better understand complex hydrodynamics that can lead to safer and more energy-efficient pulp and paper manufacturing.

Embraer uses it to drive fully immersive virtual reality (VR) for engineering analysis, simulation and virtual testing.

And DaimlerChrysler used it to help fuel its triumphant return to NASCAR's Nextel stock car circuit after a 25-year absence.

It's extreme visualization, and, thanks to a combination of greater computing power at lower costs, major software advances, compatibility with major CAE solvers and ability to run on a variety of computing platforms, the technology is revolutionizing the way engineers and scientists see, analyze, communicate and interact with their computational results.

The Democratization of Visualization

Over the last 10 years, a remarkable transformation has occurred in high-end visualization: Capabilities that once were available only to a select few now are accessible to almost anyone on any platform for any simulation application.

Animated visualizations can be generated for CFD, FEA, crash analysis or even coupled simulations combining results from different vendors' simulation programs. Displays can range from a standard color screen to stereo using low-cost glasses to immersive virtual reality devices such as PowerWall and CAVEs.

Computing can be done on anything — from a laptop equipped with a decent graphics card to a desktop PC of any flavor (Windows, Linux or Mac OS X), to a high-end workstation cluster with dozens of nodes or high-capacity, shared-memory processors.

The power of visualization is no longer limited to analysts or visualization specialists. Free software such as EnLiten from Computational Engineering International (CEI) enables scientists and engineers to share their work with colleagues to create a greater understanding of problems and solutions.

A Quiet Revolution

The revolution in visualization did not announce itself with fanfare like the dot.com boom, and it didn't suffer from the bloated expectations that made the dot.com bubble burst. Instead, it occurred through steady building over the years, and the peak isn't anywhere in sight. Advances in visualization and growing user benefits are making strong progress year by year.

“People are awakening to the power of visualization,” says Kent Misegades, CEI president, “and with that awakening come new applications, new customers and greater penetration into the mainstream of large engineering, research and scientific organizations.”

As the technological and market leader in extreme visualization, CEI serves as a good benchmark for progress in this field. Here are just some of the milestones that have been achieved over the last six years:

    — Los Alamos National Laboratories and CEI break the one
    billion cell barrier for visualization in 1999 and reach 11.5 billion
    cells a year later. Eyes are now on 100 billion cells,
    inconceivable a decade ago.

    — Free tools such as EnLiten enable complex 3-D models and
    animations to be viewed and manipulated by anyone within the
    enterprise — even novices who don't have any visualization
    application on their desktops.

    — CEI's EnSight becomes available on 64-bit computers, enabling
    more complex visualizations with multivariate data to be cached on
    desktop systems.

    — Extreme visualization comes to the Apple Mac OS X, enabling
    animations generated on high-end servers to be shared with Mac
    users at home or on the road. CEI now provides interchangeable
    visualization tools for any computing platform and operating
    system.

    — A parallel rendering compositor developed by CEI achieves a
    world-record rendering speed of 3.17 billion polygons per second
    on a cluster of 76 standard PCs.

    — CEI folds its distributed rendering technology into a product
    called EnSight DR, the first commercial visualization application
    to bring parallel graphics to the user's desktop.

    — New features such as ray tracing and multiple lighting sources
    increase image realism, making it easier to communicate complex
    concepts to non-technical audiences.

Complementary Technologies

High-end visualization on EnSight is accessible to ANSYS and other CAE solver users through freely available interfaces provided by CEI. As a result, the strength of CFD, FEA and crash analysis simulation is complemented by the capabilities of EnSight.

“ANSYS products and EnSight scale very well on huge problems that are typical of the markets we serve,” says Marcus Reis of Engineering Simulation and Scientific Software (ESSS), a leading distributor of ANSYS and CEI software that provides simulation and visualization solutions for companies such as General Motors, Petrobras, Embraer, Embraco (Whirlpool), Electrolux and others. “Our customers have very demanding applications that require them to be able to quickly and easily visualize multiple results files with extensive transient analysis from ANSYS CFX and other software.”

A recent project initiated by Silicon Graphics Inc. (SGI), CEI, ESSS and Matthew Koebbe, a consultant with GADAB Engineering, shows how extreme visualization can be used to understand fluid flows that cannot be accurately predicted by other testing methods.

Embraco of Brazil, a supplier of compressors and other products for Whirlpool, wants to better understand the flow within the suction muffler of a small hermetic refrigerating compressor used in household appliances. The challenge undertaken by Embraco researchers Fabian Fagotti and Celso Kenzo Takemori is to capture pressure fluctuations, such as noise, over a broad range of frequencies. Although this might sound relatively simple, just simulating internal pressures up to 10 MHz at various points could require a mesh of nearly 5 million nodes and 80,000 time steps.

ESSS is starting with a more coarse mesh and refining the model to see how far state-of-the-art computer technology can go in addressing Embraco's problem. ANSYS CFX was chosen as the solver because of its reputation for resolving fine-scale turbulent behavior. EnSight was selected as the visualization tool for a number of reasons, including its handling of complex and transient simulations, ability to read in results of multiple simulation cases for direct comparison and support of a scripting language for batch processing. SGI Prism hardware was used for the initial computing work.

Early results for the project are promising. Simulations showed pressure behaving as expected based on real-world use, and phenomena that couldn't be determined by experiments have been simulated in the computational realm. Quantified estimates of leakage, for example, have been determined by analysis of mass flows. Color-coded pathlines generated by EnSight are providing a better understanding of mixing within the compressor.

ESSS currently is working with Embraco to determine future directions for the project, although the initial stage already has fulfilled a major benefit of extreme visualization: enabling customers to see what they couldn't see before.

From Extreme to Pervasive

Although tremendous progress has been made in visualizing complex problems, in some ways the most exciting developments are still to come. Capabilities such as parallel processing, distributed rendering, photorealistic imaging and highly sophisticated animations not only are making their way to the desktop, but are being implemented so the complexities are hidden from the user. There will be more going on than ever before behind the nice, simple-to-use graphical user interface (GUI) — but the user will be blissfully unaware of it.

Some of the things that CEI is working on include greater parallel processing automation, GUI customization that speeds access to commonly used functionality, 2-D texture maps that increase image realism, lower-cost software for small shops and consultancies, and greater flexibility in compiling and editing animated videos.

“What we call 'extreme visualization' today will be commonplace, transparent and pervasive in the near future,” says Misegades. “We are automating the process to such an extent that 'post-processing' will be an extinct phrase — any engineer, scientist or researcher will be able to take results from practically any solver and easily turn out beautiful and revealing 3-D animations with little effort and few specialized skills.”

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Bob Cramblitt is principal of Cramblitt and Company (www.cramco.com), a technology communications firm. His articles on computer graphics, CAD/CAM, IT and other technology subjects have appeared in trade journals and Web sites worldwide.