ULTRASONIC SCATTERING FROM SPHERICAL-SHELLS INCLUDING VISCOUS AND THERMAL EFFECTS

An analysis for sound scattering and attenuation by shell structures i mmersed in fluids is outlined. While the form of the analysis permits easy comparison with previous results for simple spheres, it includes novel features of viscoelasticity in the shell and core materials (whi ch may be fluid or solid), viscosity in the suspending fluid, and ther mal effects. The computational procedure adopted is outlined with part icular reference to the avoidance of numerical instabilities at very l ow and very high values of ''ka.'' The testing of the program by compa rison with previous results on simpler systems is reported, and a limi ted selection of numerical results is given. The program has been used successfully over the range of ka values between 10(-6) and 200, its robustness needs closer definition.