Thursday, March 01, 2007

From the Labs: Information Technology

New publications, experiments and breakthroughs in information technology--and what they mean.

By Kate Greene

The spinning liquid in this snow globe is the product of a new animation technique developed at Caltech. The researchers say their geometric approach yields more realistic simulations of moving liquid. Credit: Mathieu Desbrun, Applied Geometry Lab, CalTech

More-Realistic Fluid Animations
A new approach helps computer-animated fluids flow more naturally

Source: "Stable, Circulation-Preserving, Simplicial Fluids"
Mathieu Desbrun et al.
ACM Transactions on Graphics 26(1)

Results: Researchers at the California Institute of Technology have developed a new geometric approach to simulating fluid flow that's more realistic.

Why it matters: Numerical approaches commonly used in computer animation and in aerodynamics simulations contain inaccuracies that can cause graphically depicted liquids to appear to flow unnaturally. For instance, when used to model whirlpools, these equations predict an exaggerated decrease in energy, so animations of swirling water slow down for no apparent reason. Animators need to spend time correcting these errors by hand. A numerical treatment that better respects liquids' actual behavior could save animation studios time and money.

Methods: The researchers used a new type of mathematics called discrete differential geometry to calculate the flux of a flowing liquid, a property that determines the velocity and position of the liquid at any time. The researchers say that because their equations use flux, rather than just fluid velocity, they more accurately capture the behavior of swirling liquids.

Next steps: The new approach should yield simulations that better predict the flow of fluids--say, water or air turbulence around planes or boats. Eventually, the approach could be incorporated into software for movie studios, but that will require more research on how to modify the equations to simulate a wider range of natural phenomena.