Numerical Methods for Coupled Surface and Grain Boundary Motion

Abstract

We study the coupled surface and grain boundary motion in a bicrystal in the context of the "quarter loop" geometry. Two types of physics motions are involved in this model: motion by mean curvature and motion by surface diffusion. The goal is finding a formulation that can describe the coupled motion and has good numerical behavior when discretized. Two formulations are proposed in this paper. One of them is given by a mixed order parabolic system and the other is given by Partial Differential Algebraic Equations. The parabolic formulation constitutes several parabolic equations which model the two normal direction motions separately. The performance of this formulation is good for a short time simulation. It performs even better by adding an extra term to adjust the tangential velocity of grid points. The PDAE formulation preserves the scaled arc length property and performs much better with no need to add an adjusting term. Both formulations are proven to be well-posed in a simpler setting and are solved by finite difference methods.