Quasi-Lagrangian Rezoning of Fluid Codes Maintaining an Orthogonal Mesh

The construction of suitable algorithms for integrating hydrodynamic equations on an arbitrary time varying orthogonal mesh is investigated, with particular attention to the case where the mesh is moved with a minimum of slip. The form of mesh required to maintain a consistent and conservative difference is discussed, and algorithms satisfying these constraints are investigated. A general form in which the fluid is transported by a Lagrangian difference and then rezoned back on to the modified grid is studied. Particular attention is paid to the merits of the SHASTA-FCT algorithm for rezoning, and its use in a fully Lagrangian system without artificial diffusion is discussed.