Esther de Jong
Simulating Snow with the Material Point Method
This thesis discusses the research and development steps for the simulation of snow with the Material Point Method (MPM). In order to gain an understanding in the technique and mathematics the MPM was researched in detail. All ten steps of the MPM were implemented using C++. First the method was implemented without the collision and implicit update. Next the body-collision for the particles and grid nodes were applied and last the semi-implicit update step was applied. The goal of implementing and understanding all the steps of the MPM was obtained. Test were done with snowballs: letting them drop, throwing them against a wall and throwing a small snowball against a static bigger snowball. The two snowballs interacted and the big snowball was pushed back by the small snowball while the small snowball also created a hole in the big snowball. The collision worked correctly for the grid nodes and particles. Finding the balance between the number of particles, their weight and the size of the grid nodes was challenging and while this was improved the simulations improved too and became more realistic. The results were not completely satisfactory yet and when the snowball was dropped shear and velocity decrease was observed after a few frames. This problem could not be solved within the available time. Although the snow characteristics where not completely reached the Lagrangian particle and Euler grid implementation that is the basis of the MPM method was successful.