A Numerical Study of the Dynamics of Detonation Initiated by Cavity Collapse

The dynamics of detonation evolution in a condensed-phase explosive, initiated by the shock-induced collapse of an embedded, ellipsoidal, gas-filled cavity, is examined computationally. Attention is focused on the details of the evolutionary process following the collapse. The reaction rate is assumed to be pressure-dependent, switching on when the pressure exceeds an ignition threshold. The strength of the incident shock is taken to be such that the reaction would not be initiated without the interaction of the shock with the cavity. The system is modeled as a multi-material mixture, and a high-resolution, Godunov type capturing scheme is employed to solve the governing equations numerically. The computations are carried out in parallel, and adaptive mesh refinement is used to obtain accurate and well-resolved solutions. It is found that collapse of the cavity produces a detonation provided the cavity is large enough, or the rate of reaction strong enough; otherwise reaction initiated by the collapse fizzles out. Details of how the detonation is is established are found to depend strongly upon the shape of the cavity.