Tank experiments for validation of volume scattering models.

Abstract

Mid-frequency scattering from random media is of interest for active sonar applications and, in particular, in shallow water environments, where ocean bottom interaction may affect the performance. To estimate the contribution of volume scattering from the sea bed, models based on the wave equation have been developed and more recently, an approach based on transport theory was proposed [J. Acoust. Soc. Am. 126, 1711–1723 (2009)]. Validation of this model is difficult to achieve in field experiments due to environmental uncertainties and in many cases to the lack of ground truth revealing the structure of the random media. As an alternative, tank experiments were implemented in a controlled environment at scaled frequencies to explore the range of applicability as a function of different input parameters such as frequency of operation, scatterer size, and concentration. For this work, gel slabs containing random distributions of micron-sized glass beads were manufactured, and broadband pulses at the frequency band 200–600 kHz were utilized to characterize the scatterer contribution. Acoustic propagation through this heterogeneous media is analyzed using the proposed radiative transfer method and the results are compared to the analytical solution of the wave equation for the long-wavelength approximation.