Towards real-time simulation of interactions among solids and fluids.

摘要

The interactions among fluids and solids create many interesting phenomena that are excessively complex for manual creation in animation. It is popular to model these interactions in physically based simulation but it is challenging especially in real-time applications. Collisions handling is a major bottleneck for solid-solid interaction problems because of high computational cost of neighbor searching in space. Solid-fluid interactions are also difficult to simulate mostly because of the difference in representations of fluids and solids. Typically simulation systems use Eulerian methods for fluids and Lagrangian methods for solids. The most adopted coupling strategy uses solid velocity as boundary condition in fluid solver and integrate fluid pressure along solid boundary to apply force on solid. However, the quality of fluid animation is limited by resolution of Eulerian grid thus it cannot handle interaction with thin features on solids.;In this dissertation we focus on specific types of interactions among fluids and solids and develop simulation methods with improved quality and performance toward real-time applications. First we address the problem of cloth, air, and deformable body interactions modeling in a layered structure as commonly seen in real world. We develop an accelerated collision detection method taking advantage of the layer structure to improve efficiency and an accurate anisotropic friction model to achieve fine contact details. The interaction of air and other layers is modeled using a fast air mass field model. Next, we turn to fracture simulation in solid-solid interaction, which is known to be computationally expensive in high resolution. We develop a surface refinement approach that adds fine details to existing low-resolution fracture animation with negligible extra computation cost. Finally, we explore coupling of fluid and solid with thin features. We take a stable and fast approach that couples hybrid Eulerian-Lagrangian fluid and position based solids. The approach shows its effectiveness in modeling the paint-brush interactions in a real-time oil-painting simulation system.