Subcritical penetration into rough seafloors due to Bragg scattering

A tank experiment and theoretical analysis are carried out to study acoustic Bragg scattering by a sinusoidal surface with period 0.3 m and amplitude 2 cm between water and sand sediment. The penetrating field is measured in the frequency range from 20 to 40 kHz at grazing angles 10° to 90° in the tank. A theoretical solution for acoustic scattering by the sinusoidal surface is derived to explain the interference pattern observed in the experiment. The result shows that the minus first order Bragg scattering wave is strong enough to interfere with the refracted wave obeying Snell's law, forming interference patterns that can be detected experimentally.