Simulation of shock initiation in explosives using a model combining high computational efficiency with a free choice of mixture rules

Models for shock initiation in explosives must consider how energy transfers from products to reactants. This is based on different energy-apportionment assumptions, which affect the results for shock initiation. This study proposes a robust model of shock initiation in explosives using a free choice of energy-apportionment assumptions. The reacting explosive is treated as a mixture of reactants and products under different energy-apportionment assumptions. The equations of state of the mixture are efficiently solved by refining the Cochran-Chan concept of the real volume fraction and introducing a real energy fraction term. The validity, efficiency, and universality of the proposed model are verified in one-dimensional numerical simulations of the shock initiation of homogeneous (nitromethane) and heterogeneous (PBX 9404) explosives. Compared to the conventional Cochran-Chan and Johnson-Tang-Forest models, the proposed model has a better balance of computational efficiency and universality.