Numerical Simulation of Sonic Boom from Hypersonic Meteoroids

摘要

Meteoroids entering the Earth atmosphere at high hypersonic velocities are sources of sonic booms that are recorded as infrasound signals at the ground level. The boom pressure field is simulated by solving Euler equations for a spherical meteoroid. The numerical challenge is to capture the acoustical regime of weak shock waves in the very far field at several hundreds or thousands times the meteoroid diameter. Computational fluid dynamics simulations are then matched to nonlinear geometrical acoustics for long-range atmospheric propagation down to the ground. The numerical process is validated through comparison with an analytical model, considering for perfect gases the meteoroid as a line source of strong shock in the near field, matched to a weak shock N-wave in the far field. Compared with a perfect gas, real gas effects at thermochemical equilibrium induce a reduced amplitude at the source, along with a shorter signal duration at the ground level. Simulations are illustrated for the well-documented Carancas meteorite that impacted on Peru in 2007.