Shock-induced collapse of porosity, mapping pore size and geometry, collapse mechanism, and hotspot temperature

Abstract

We use molecular dynamics simulations to characterize the shock-induced collapse of porosity of 1,3,5,7-tetranitro-1,3,5,7-tetrazoctane. We focus on how pore size and shape affect the collapse mechanism and resulting hotspot temperature distribution. Within the hydrodynamic collapse regime, for particle velocities above 0.7 km/s, we find that a combination of the curvature of the downstream surface and void length affects the terminal velocity of the expanding material and, consequently, temperature. Increasing curvature and length result in faster speeds, including jetting, and higher temperatures. For long and thin voids, there is a maximum in temperature with curvature as lateral collapse restricts the expanding material. The simulations map void size and shape to the resulting hotspot and provide a key piece of information toward the development of predictive modeling of shock-induced initiation.