Distributed point source method and its applications in solving acoustic wave scattering problems

Abstract

A recently developed semi-analytical technique called distributed point source method is used for solving various wave scattering problems. Scattering of focused ultrasonic fields by air bubbles or cavities in fluid and solid media is investigated in this presentation. Results for both single and multiple cavity geometries are presented. It is investigated when two cavities in close proximity can be distinguished and when it is not possible. The interaction effect between two cavities prohibits simple linear superposition of single cavity solutions to obtain the solution for the two cavities placed in close proximity. Therefore, although some analytical and semi-analytical solutions are available for the single cavity in a focused ultrasonic field, those solutions cannot be simply superimposed for solving the two-cavity problem even in a linear elastic material. The comparison between the ultrasonic energies reflected from two small cavities versus a single big cavity is also investigated. Detection and characterization of cavities is important for both materials science and medical applications because air bubbles in molten metal as well as in blood must be first detected and characterized before taking necessary actions.