Applications ranging from commercial entertainment to surgical training demand efficient methods for realistically modeling the appearance of physical phenomena in synthetic environments. In this talk I will describe methods we have developed for simulating the behavior of a wide class of materials known as viscoelastic fluids. These materials, such as mucus, liquid soap, pudding, toothpaste, or clay, exhibit a combination of both fluid and solid characteristics. Like a solid they can resist strain elastically, but under large or sustained strains they flow like a fluid. Our methods builds upon prior Eulerian techniques for animating incompressible fluids with free surfaces by including additional elasto-plastic terms in the basic Navier-Stokes equations. These terms are computed by advecting integrated strain-rate throughout the fluid. Transition from elastic resistance to viscous flow is controlled by von Mises's yield condition, and subsequent behavior governed by a time-dependent quasi-linear plasticity model.
I will also briefly describe other simulation techniques for modeling phenomena such as explosions, fracture, real-time deformation, and even sound. One issue that arises recurrently is that all of these simulation techniques require clear geometric descriptions of the objects and environments they model. To address this need I will show how highly detailed implicit surfaces can be built from defective input models using moving-least-squares interpolation techniques.
