Constraint-based simulation of interactions between fluids and unconstrained rigid bodies

We present a method for simulating stable interactions between fluids and unconstrained rigid bodies. Conventional particle-based methods used a penalty-based approach to resolve collisions between fluids and rigid bodies. However, these methods are very sensitive to the setting of physical parameters such as spring coefficients, and thus the search for appropriate parameters usually results in a tedious time-consuming task. In this paper, we extend a constraint-based approach, which was originally developed for calculating interactions between rigid bodies only, so that we can simulate collisions between fluids and unconstrained rigid bodies without worrying about the parameter tweaking. Our primary contribution lies in the formulation of such interactions as a linear complementary problem in such a way that it can be resolved by straightforwardly employing Lemke's algorithm. Several animation results together with the details of GPU-based implementation are presented to demonstrate the applicability of the proposed approach.