Cavitation begins with nucleation, i.e. the origin of microscopic spaces that can form nuclei for the growth of macroscopic bubbles that will collapse later. Normally these form in the border area, between the liquid and the solid surface with which it is in contact or between the fluid and the particles suspended in it.
Nucleation can occur in the following ways:
- homogeneous, when the thermal motions inside the liquid temporarily constitute microscopic voids that can subsequently constitute the nuclei necessary for the growth of macroscopic bubbles
- heterogeneous, if it is favored by the presence of microparticles dispersed in the primary fluid or caused by the roughness of the walls of the duct that contains the fluid
The expansion of the bubble is essentially due to the difference between the pressure inside it and the pressure in the surrounding liquid.
Its subsequent collapse starts immediately at the end of the expansion phase. Cavitation culminates in an implosion that can cause serious damage.
The high stresses that are generated on the fluid and on what is suspended in it, cause the destruction / breakage of the cell structures placed in contact.
