Numerical study of spherical blast-wave propagation and reflection (Q1849286)

The objective is to understand the flow structures of weak and strong spherical blast waves either propagating in a free field or interacting with a flat plate. A fifth-order weighted essentially non-oscillatory scheme with a fourth-order Runge-Kutta method is employed to solve compressible Euler/Navier-Stokes equations by a finite volume approach. A high-resolution Euler/Navier-Stokes solver with a real-gas model is developed and used to investigate the propagation of a spherical blast wave in the free field and the reflection phenomenon of the blast wave when interacting with the flat plate. The solver is validated to be reasonably accurate on several test problems. For the problem of blast-wave propagation in the free field, it is found that three outward-moving weaker shock waves develop behind the primary shock wave, and a contact surface is formed. For the problem of weak blast-wave interaction with the flat plate, the authors observe complicated shock-shock interactions in addition to the basic flow structure for the blast-wave propagation in the free field. Moreover, it is found that there is a transition from regular reflection to Mach reflection in a turbulent flow, delayed compared with that for inviscid flow or for laminar flow. For the problem of strong blast-wave interaction with flat plate, the authors investigate a complicated flow structure associated with the transition from regular reflection to double Mach reflection. It is found that near the flat plate there are at least three local high-pressure regions behind the curved Mach stem, resulting in an over-turning effect in addition to the crushing effect in very high explosions.