"Simultaneous Coupling of Fluids and Deformable Bodies"

In this sketch, we present a novel method for simulating the two-way interaction between fluids and deformable bodies. The key to this method involves setting up a system of equations that simultaneously conserves the momentum of the fluid and deformable bodies while also enforcing conservation of mass. Previous approaches use a time splitting procedure. They alternately fix the fluid pressure while simulating the solid, then fix the solids velocity while simulating the fluid. While this approach can work well for physical systems with non-stiff coupling, it can lead to instability and visual artifacts for more stiff systems. These problems occur because while solid velocities are fixed they will ignore arbitrarily large fluid pressures, and the converse when the fluid velocities are fixed. Time splitting also requires non-physical fixes for systems that include fluid regions completely surrounded by a deformable body. By enforcing simultaneous coupling our method avoids these artifacts and allows for substantially larger time steps.

Chentanez, N., Goktekin, T.G., Feldman, B.E., O'Brien, J.F. "Simultaneous Coupling of Fluids and Deformable Bodies." To appear in ACM SIGGRAPH 2006, Boston, Massachusetts,July 30 - August 3, 2006. Technical Sketch