Abstract:

Multiple scattering owing to strong sediment volume inhomogeneities is discussed using the formally averaged approach, which was originated from the quantum field theory and has been extensively applied to wave propagation in random media. Random spatial variations of sediment density as well as sound speed are considered. While it is well known that the sound-speed variations result in a renormalized complex wave number, when the coherent field is concerned it is found that the density variations can also be renormalized, but they manifest themselves as a formal density gradient in the wave equation. This can be identified as a new loss mechanism of the coherent field. When both sound speed and density variations are included, the cross correlation between sound speed and density is an important quantity to measure since it will influence the scattering intensity to a non-negligible extent. Numerical examples will be presented and discussed. [Work supported by ONR Code 321OA.]