Porosity is correlated to the ignition behavior of explosives and, consequently, pore collapse has been the mechanism often attributed to converting the mechanical energy of a passing shock into local heating for exothermic chemical reactions. While pore distributions are experimentally measured, the subset active in ignition should be bracketed for the potential use in reactive flow models that consider such physical parameters as pore size in an effort to be more predictive. Thermal explosion theory has examined the issue of pore criticality mathematically with necessary simplifications (isolated pores, uniform temperature fields, constant physical parameters, etc.). Avoiding such simplifications by coupling a multiphysics-capable hydrodynamics code (ALE3D) with a chemical kinetics solver (CHEETAH), we can parametrically analyze different pore sizes undergoing collapse in high pressure shock conditions with evolving physical parameter fields. For the analyzed pore sizes, ignition mechanisms are monitored and the regimes of pore sizes that contribute significantly to burnt mass faction and those that survive thermal conduction to continue to burn on the time scales of ignition are elucidated. Comparisons are drawn between the thermal explosion theory and the multiphysics models for the determination of nominal pore sizes that burn significantly during ignition for the explosive l,3,5-triamino-2,4,6-trinitrobenzene (TATB).
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