An Eulerian algorithm for coupled simulations of elastoplastic-solids and condensed-phase explosives
The performance of non-ideal condensed-phase explosives depends on the nature of the confiner material as well as the charge itself, so the accurate modelling of this confiner and its interaction with the explosive allows for improved performance predictions. Traditionally, numerical methods for solving such multi-material problems have used Lagrangian or mixed EulerianLagrangian approaches, but recent advances in numerical methods for coupling CFD (Computational Fluid Dynamics) and CMD (Computational Material Dynamics) algorithms has made such coupled simulations possible in the Eulerian frame of reference. However, to date, the explosive material representation within these simulations has been restricted to the single-phase Euler equations. In the present study we couple a multi-phase chemically-active model for condensed-phase explosives to an elasticplastic model for inert confiner materials. In the presented algorithm, the ghost-fluid method is employed to represent the evolving material interfaces as discontinuities on discrete space. The coupling between the materials at these interfaces is achieved by means of a new approximate mixed Riemann solver, developed as part of this research. In addition we present a mixed Riemann solver for a simpler transport model, which ignores compaction effects at the interface. The robustness and accuracy of the developed solvers is demonstrated by comparisons against results from the original ghost-fluid method and exact solutions of model Riemann problems. To allow for more realistic material behaviour, the mixed Riemann solvers are subsequently extended to handle the shock MieGrneisen equation of state, and an iterative procedure is suggested to increase accuracy as required. These mixed Riemann solvers demonstrate their suitability for explosivesolid interactions in two test cases of multi-phase detonations confined by an elasticplastic solid.
eulerian explosive multi-phase mixed riemann solver solid mechanics solidfluid coupling