Mesh-free modeling of the interaction between a point-focused acoustic lens and a cavity

Interaction between a cavity or void in a liquid and a converging ultrasonic beam generated by a point-focused acoustic lens is investigated. A semi-analytical technique called the distributed point source method (DPSM) is adopted because no analytical solution is available for this problem involving cavities of different size and the finite element method is not very efficient for modeling high-frequency ultrasonic problems. The solution shows that if the cavity is placed very close to the focal point of the lens then it can be detected by the acoustic lens. The detectability of the cavity at the off-focus position depends on the distance of the cavity from the focal point. The variation of this distance as the cavity moves in horizontal and vertical directions from the focal point is also investigated.