REZONE: A method for automatic rezoning in two-dimensional Lagrangian hydrodynamics problems

A method for automatic rezoning in two-dimensional Lagrangian hydrodynamics problems is described. This method conserves mass, internal energy, and directed kinetic energy as these quantities are transferred from one zone to another. The general procedure is to run the problem hydrodynamically while monitoring the mesh for distortion. When the distortion becomes severe, the problem is interrupted and the REZONE code takes over to clear up the mesh distortion. This process is continued as needed during the entire run of the problem. Only those areas of the mesh that show distortion are rezoned. The purpose of this method is to keep hydrodynamic problems running while disturbing the normal calculations as little as possible. With this method the overall shape of the mesh will still indicate the natural flow of the hydrodynamics problems.