Numerical and experimental study on wave propagation in granular media using a spectral-element method

Acoustic systems with various operating frequencies are commonly used for the detection of objects buried in the marine sediments. However, the propagation of acoustic waves in sediments is generally much more complicated than in water because sediments are, in general, granular media composed of solid and fluid parts. It makes the understanding of signals more difficult and engineers have to rely on a cut-and-try method for the design of the new sub-bottom devices which results in an increase of the total cost of sea surveys. Therefore, a better understanding of wave propagation in the granular media and of the numerical model used for the prediction of reflected signals from buried objects is required. In the present study, we evaluate the performances of the prediction tools based on the spectral element method for the simulation of backscattered signals by comparing them to experimental results obtained in a tank filled with water and calibrated glass beads having a wide range of ratio of the grain size to the wavelength.