Réflexion et refraction d'ondes acoustiques par une onde de choc

Sound waves in one or other of the fluid regions on either side of a shock wave are made apparent in the region under excess pressure by acoustic waves (reflected or refracted according as the incident waves he in the region of pressure excess or defect) and by thermal waves. The characteristics of these waves are calculated for a plane, progressive, uniform incident wave. In the refracted case, the refracted acoustic wave can, according to the incidence, be plane, progressive and uniform or take the form of an “onde d'accompagnement” which remains attached to the front of the shock while sliding parallel to it. Geometric constructions allow in each case the kinematic characteristics of the reflected or refracted acoustic waves to be determined. Dynamic relationships show that the amplitude of the reflected wave is always less than, but that of the refracted wave in certain cases greater than, the amplitude of the incident wave.