Cavitation is a phenomenon that occurs in fluids when the static pressure of a liquid reduces to below the liquids vapor pressure, leading to the formation of small vapor-filled cavities in the liquid. These cavities can grow and collapse due to local pressure fluctuations, producing a low pressure in the form of vapor pressure of the fluid. There are two principal types of cavitation: vaporous and gaseous. Vaporous cavitation is an ebullition process that takes place if the bubble grows explosively in an unbounded manner as liquid rapidly changes into vapor. Cavitation can be controlled to enhance the performance of high-speed marine vessels and projectiles, as well as in material processing technologies, in medicine, etc. . However, cavitation is usually an undesirable occurrence that can disturb the normal operating conditions of fluid-type mechanical systems and destroy the surfaces of components.

Cavitation can be classified into different types based on the energy input and the process of vaporization, bubble generation, and bubble implosion. Some of the common types of cavitation are:

• Non-inertial cavitation: This is the process in which a bubble in a fluid is forced to oscillate in size or shape due to some form of energy input, such as an acoustic field. Such cavitation is often employed in ultrasonic cleaning baths and can also be observed in pumps, propellers, etc. .

• Hydrodynamic cavitation: This is the process of vaporization, bubble generation, and bubble implosion which occurs in a flowing liquid as a result of a decrease and subsequent increase in local pressure. Cavitation will only occur if the local pressure declines to some point below the saturated vapor pressure of the liquid and subsequent recovery above the vapor pressure. If the recovery pressure is not above the vapor pressure then flashing is said to have occurred.

• Discharge cavitation: This occurs when pressure at the discharge end of the pump is too high. High discharge pressure limits the volume of fluid.

Cavitation can cause significant damage to mechanical systems, including pumps, turbines, and marine propellers. The sudden growth and collapse of vapor cavities can cause extreme pressures that pit the metal surfaces exposed to the cavitating liquid. To prevent cavitation, it is important to maintain a positive net suction head available (NPSHa) and avoid blockages or restrictions such as clogged filters or part-closed valves.