Reflection of weak Shockwaves from a rough surface

摘要

This paper adresses the problem of the reflection of acoustic Shockwaves from rough surfaces. For this purpose, the 2D Euler equations are solved using curvilinear coordinates. A source representative of spark-generated shock waves is implemented. The reflexion pattern is first analyzed and compared to that from a smooth surface. For small roughness, a Mach stem is formed and the evolution of its height with the propagation distance is investigated for several sets of roughness parameters. As for a smooth surface, the Mach stem height increases with the propagation distance but grows more and more slowly as the roughness characteristic length increases. For a sufficiently large roughness, the Mach stem is no longer observed. The waveforms and corresponding spectra are then studied. It is concluded that the roughness tends to decrease the peak overpressure and the rise time and to increase the signal duration.