Overset Mesh Method for Arbitrary Lagrangian Eulerian Contact on Unstructured General Polyhedral Meshes

Abstract We present an overset mesh method for Arbitrary Lagrangian Eulerian (ALE) hydrodynamic contact on unstructured polyhedral meshes in the FLAG hydrocode at LANL. This capability enables simulations of contact and sliding between materials where one or both materials deforms too severely for a pure Lagrangian simulation, e.g. simulating penetration experiments. The overset mesh method couples two ALE meshes by applying contact forces at material boundaries to resist material penetration while conserving mass, momentum, and energy of the combined system. It accommodates any pair of conformal free surfaces and subzonal material interfaces, in 1D, 2D and 3D, in Cartesian and axisymmetric (1D spherical and cylindrical, 2D cylindrical) geometries, for unstructured general polyhedral meshes. The method is parallelized with a rendezvous decomposition to allow each mesh to be arbitrarily decomposed. We perform verification and validation tests with a variety of gas dynamics simulations and compare 2D and 3D overset simulations to experiments of high velocity solid penetration, showing good agreement in penetration depth and penetrator deformation and capturing a range of penetration phenomena.