A. Bargteil and M. van de Panne (Editors) A Multigrid Fluid Pressure Solver Handling Separating Solid Boundary Conditions

We present a multigrid method for solving the linear complementarity problem (LCP) resulting from discretizing the Poisson equation subject to separating solid boundary conditions in an Eulerian liquid simulation’s pressure projection step. The method requires only a few small changes to a multigrid solver for linear systems. Our generalized solver is fast enough to handle 3D liquid simulations with separating boundary conditions in practical domain sizes. Previous methods could only handle relatively small 2D domains in reasonable time because they used expensive quadratic programming (QP) solvers. We demonstrate our technique in several practical scenarios in which the omission of separating boundary conditions results in disturbing artifacts of liquid sticking to walls.