Naval Res. Lab., Washington, DC 20375-5350
An algorithm is developed to compute the field scattered from a rigid target placed in shallow water. The method of superposition is applied where the scattered field is approximated to be equivalent to the field produced by a large number of point sources placed on a surface inside the target. The source strengths are determined by minimizing the least-squares error of the normal velocity on the surface of the target. This algorithm is applicable even when the source or the receiver is close to the target as well as in the case where the target is close to the surface. Scattering computations are made for a cylinder with hemispherical 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 Ingenito [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 methods agree in the range of applicability of Ingenito's method.