Diffraction of Acoustic Pulses by Obstacles of Arbitrary Shape with a Robin Boundary Condition

The diffraction of arbitrary plane acoustic pulses by arbitrary scattering obstacles whose boundary offers inertial but no elastic resistance is considered. The specific problem of a long cylinder of square cross section struck laterally by a unit step pressure pulse is solved numerically in two forms: Part A—the surface pressure distribution is obtained for “heavy” scatterers; and Part B—the surface normal velocity is found for “light” scatterers. There is a region of overlap where either form is applicable. The results indicate that a change in surface mass density has a significant effect on the pressure solution for heavy scatterers but that the velocity solution for light scattering obstacles remains very close to the solution for a completely free scattering surface for a wide range of surface mass densities.