Multi-Scale Coupling Strategies for Multi-physics Simulation Tools

The goal of this proposal is to conduct basic research into multiscale coupling strategies of computational tools used in the numerical simulation of energetic materials. The focus will be on predicting the flow dynamics of a blast wave emanating from a device containing energetic materials with embedded aluminum particles and the subsequent particle-laden flow to a target. The overall numerical framework will link molecular dynamics calculations for individual species all the way up to macroscale blast wave propagation and impact on a target. Small scale simulations will be used to identify important processes and develop key parameters for larger scale simulations. Thus a theoretically based numerical framework will be developed. Research will be conducted to identify critical information needed at each scale and to develope methods to extract that information from smaller scales. Minimizing computation burdens on larger-scale simulations is also an important consideration. In addition to investigating coupling strategies, we will conduct basic research corresponding to each of the separate physics pieces to increase their fidelity with regards to the specific problem of interest.

The detonation of an explosive is a complex process that requires advanced computational tools to simulate detail. The complex microstructure of most energetic materials, which have explosive crystals packed in a polymeric binder, makes this particularly challenging. Any detailed numerical conservation law solver must be able to represent the complex disparate geometries, equations of state, and chemistries of the constitutive energetic materials. With this motivation, we have developed RocSDT, a Eulerian fixed-mesh numerical solver designed particularly for simulation of condensed phase detonation in micro-structured explosives. The mass, momentum and energy conservation laws are discretized within a finite-volume method built upon the shock-capturing HLLC approximate Riemann solver. Such a solver is well-suited to the highly distorting (i.e. flowing) energetic materials in the explosive.