A Moving Least Squares Material Point Method for Varied Porous Material Interactions and Non-sticky Coupling of Phases

Abstract

The Material Point Method (MPM) has become very popular in computer graphics due to its capability to handle a variety of materials and ease of coupling for multi-material simulations. However, MPM suffers from numerical stickyness, which is especially apparent in fluid-solid coupling. Furthermore, the free-flowing nature of fluids can cause issues for simulating immiscible fluids, leading to improper separation of phases especially at lower resolutions. Furthermore, some MPM formulations suffer from unwanted dissipation, noise or instability. Our MPM framework solves the latter using the Moving Least Squares MPM, while the former is addressed by coupling two grids only on contact, with an optional friction term for tangential coupling. This is further enhanced with a buoyancy penalty force that can achieve clean separation of immiscible fluids even at low resolutions. We combine this with a method for porous solids which we generalize in order to allow for highly varied material interactions.