B. S. Sridhara
Ind. Studies Dept., Middle Tenn. State Univ., Murfreesboro, TN 37132
Sadasiva M. Rao
Auburn Univ., Auburn, AL 36849
Far-field scattered properties for a rigid sphere coated with several layers of absorbing materials have been obtained using the eigenfunction expansion method. The sphere coated with m number of acoustic layers and placed in air, in a lossless situation, was considered. Compatibility conditions of sound pressures and sound velocities were applied at layer interfaces. The resulting (2m+1) complex linear algebraic equations involving material properties, and the spherical Bessel, Newman, and Hankel functions, were written in the matrix form. Computer codes were developed and the equations were solved for the coefficients which, along with other variables and parameters, were used to compute the scattered field properties. The formulation was verified by computing the far-field scattered parameter and comparing it with the available standard results. Far-field scattered properties were computed for a rigid sphere coated with a total of 12 different layers. In each case, the magnitude of the far-field scatter parameter was computed and plotted as a function of the angle in the range from 0(degrees) to 180(degrees). It was observed that the scatter parameter was sensitive to the change in the angle and the variation was relatively large in the range from 100(degrees) to 160(degrees) in the case of certain layers.