By L. Stephen Wolfe, P.E.
Mention Siggraph and most people think of sophisticated computer graphics for making movies and videos. But technologies that may aid mechanical engineers also appear at Siggraph. Two years ago NextLimit showed off Xflow, an application for modeling fluid mechanics that’s much easier to set up and use than traditional computational fluid dynamics (CFD) software.
This year in the Intel booth, visitors had the opportunity to see another novel approach to CFD made possible by the availability of relatively low-cost computers with dozens of Intel microprocessor cores. Exocortex is a Canadian company that produces a variety of software products for data visualization and fluid simulation. Among these is Slipstream FX, a novel approach to CFD that employs an automatic, adaptive tetrahedral mesh in lieu of the Cartesian or hexahedral meshes employed by traditional CFD software.
Normal CFD meshes must be aligned with fluid boundaries and flow fields to produce accurate results. This technique requires much fussing by the analyst to get the mesh right. When the flow-field changes, as it does unsteady flows, analysts must revise or recreate the CFD mesh.
Exocortex’s approach enables the tetrahedral mesh to be quickly and automatically refined and redefined in regions where the flow velocity changes rapidly. Consequently, the software is able to model complex phenomena such as breaking waves and water sloshing in a tank.
The rapid refinement is made possible by dividing the mesh-generation and CFD solution among multiple processors. In the Siggraph demonstration, the Intel computer had 24 cores. Exocortex has applied for patents on the process. The technique is described in a paper presented at Siggraph, “Tetrahedral Embedded Boundary Methods for Accurate and Flexible Adaptive Fluids.”
At this writing, Exocortex is marketing Slipstream FX to movie makers, not engineers who analyze the likes of automobiles, aircraft, and turbomachinery. Given the conservatism of the engineering analyst community, this strategy seems sensible. Movie makers don’t have to worry about wings falling off airplanes if the pressures calculated by their CFD codes are wrong. Engineers do.
However, Exocortex’s chief technology officer Ben Houston claims that Slipstream FX is physically accurate and could be applied to real-world engineering problems. This software is a striking example of how much more can be done with the growing power of multiple processors to make engineering analysis more productive.
A beta version of Slipstream FX is expected to be available soon followed by the first product release one to two months later. Houston said Exocortex would be interested in working with a partner to bring his company’s simulator to CFD engineers.