Abstract: We present an algorithm for tracking surfaces and material interfaces in two-dimensional Eulerian hydrocodes by combining the advantages of usual interface tracking methods with line segments. The main idea of the algorithm is that by defining the marker particles on cell boundaries, tracking a interface by traditional Lagrangian-type markers becomes tracking the interface by the markers at the Eulerian cell lines. We call this algorithm the Marker On Cell Line (MOCL) algorithm. In MOCL, the erosion and separation between materials are implemented by the transformation between material markers and the common markers of different materials, the sliding is approximated by using different transport velocities to different materials in a mixed cell. Moreover, the accuracy for computing material advection in the remap steps can be improved and the non-physical diffusion can be avoided by regarding the marker line in a mixed cell as the boundary of determining the fluid flux. On the other hand, some smearing effect is given by the MOCL algorithm, which can effectively tackle the numerical oscillations in mixed cells but brings only a negligible error for the interfaces. To test the algorithm, we incorporate the MOCL in a two-dimensional multi-material elastic-plastic Eulerian hydrocode (MHEP-MOCL) and present some numerical examples by the MHEP-MOCL code, including uniform motion of different objects, rotation of notched objects, jet formation from a liner and the penetration of a 10-mm-thick steel plate by the jet, and ogival and flat nose rods penetrating to concrete targets. Numerical results show that the algorithm is feasible and stable for computation of surfaces and material interfaces, in particular those materials with very complex surfaces.
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