When a liquid is created by turbulence, bubbles (cavities) containing high pressure steam are formed, which implode immediately by releasing energy in the form of steam pressure.
The mechanical vibrations produced by the PZT elements fixed on the walls of the bathtub generate in the wave liquid which, by alternating a compression phase and a subsequent decompression stage, produce a very strong turbulence.
Consequently, many cavitation bubbles are formed, which when imploded develop a pressure that was measured around 1,000 bar.
The more compression and decompression action the more energy is.
Any foreign body present on the surface of a piece immersed in the liquid is crushed, dissolved and removed.
This phenomenon is well-known and very feared in the field of naval engineering because of the corrosion that cavitation, caused by the violent whirling of the propellers, causes precisely the same propellers and that in order to overcome it special arrangements have to be made.