Edge effect

An effect whereby the acoustid effect at the edge (periphery) of a surface differs from that at the interior of the same surface.

For example, the figure below (from Young, p. 15; 25 kHz, 44.5 microns, 24 °C water) shows that the cavitation erosion at the periphery is significantly less than on the remainder of the horn's face.

Ultrasonic cavitation erosion of nickel 270
Figure 1. Cavitation erosion of nickel 270