A Bezier-Based Approach to Unstructured Moving Meshes

We present in this report a new framework for maintaining good quality of two dimensional triangular moving meshes. The use of curved elements is the key idea that allows us to avoid excessive refinement and still obtain good quality meshes consisting of a low number of well shaped elements. We use B-splines curves to model object boundaries and objects are meshed with second order Bezier triangles. As the mesh evolves according to a non- uniform ow velocity field, we keep track of object boundaries and, if needed, carefully modify the mesh to keep it well shaped by applying a combination of vertex insertion and deletion, edge flipping, and curve smoothing operations at each time step. Our algorithms for these tasks are extensions of known algorithms for meshes build of straight{sided elements and are designed for any fixed-order Bezier elements and B-splines. We discuss a calculus of geometric primitives for Bezier curves and triangles that we employ to implement such operations. Although in this work we have concentrated on quadratic elements, most of the operations are valid for elements of any order and they generalize well to higher dimensions. We present results of our scheme for a set of objects mimicking red blood cells subject to a a priori computed ow velocity field. As a pure geometric exploration, our method does not account for neither refinement nor coarsening dictated by the simulation results.