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Simulation of Ultrasonic Beam in Vortex

The shell function method is extended and adapted to evaluate the acoustic pressure field in an arbitrary inhomogeneous and moving medium. In the case of an inhomogeneous and quiescent medium, the shell function method for computing the acoustic pressure field due to a finite source was developed using the principle of reciprocity. Based on the reciprocity in a moving medium, the extension is accomplished by investigating rays as originating from an imaginary point source located at the observation point, in the medium with reversed flow direction. Through a numerical example of evaluating the pressure field in a vortex produced by a disk source, it is shown that the shell function method gives an interpretation for the beam displacement with respect to the vortex.