METHOD OF SUPERPOSITION APPLIED TO SCATTERING FROM A TARGET IN SHALLOW-WATER

An algorithm is developed to compute the field scattered from a target placed in shallow water. The method of superposition is applied where the scattered field is approximated to be equivalent to the field pro duced by a large number of point sources placed on a surface inside th e target. The source strengths are determined by minimizing the least- squares error of the normal velocity on the surface of the target. Thi s algorithm is applicable even when the source or the receiver is clos e to the target as well as in the case where the target is close to th e surface. Scattering computations are made for a cylinder with hemisp herical endcaps in an isovelocity fluid with soft boundary conditions on top and rigid boundary conditions on the bottom. They are compared to the scattered field computed by using an algorithm discussed by Ing enito [F. Ingenito, J. Acoust. Soc. Am. 82, 2051-2059 (1987)] for the case when both the source and the receiver are distant from the target and when the target is distant from the surface. Results from both me thods agree in the range of applicability of Ingenito's method.