ABSTRACT
G.F. Oweis and S.L. Ceccio Cavitation is the physical phenomenon associated with the inception, growth, and implosion of cavities (vapor-filled voids or bubbles) in the body of a flowing or a quiescent liquid due to changes in the fluid pressure. Cavitation may occur entirely in the bulk of the liquid or close to solid boundaries of the flow. Cavitation is similar to boiling in the inception and growth of bubbles, except that in the latter bubble formation is due to a rise in liquid temperature, while in the former bubble formation is driven by a drop
in the liquid static pressure. Pressure variations in the fluid can be achieved hydrodynamically or acoustically. During vaporous (inertial) cavitation, the cavities are filled mostly with fluid vapor. Vaporous cavitation bubbles are often short-lived and produce a high-intensity acoustic pressure upon collapse. Gaseous cavitation bubbles are filled mostly with noncondensible gases, and these gaseous bubbles may persist for longer periods, collapse much less violently, and produce much less noise and damage compared to vaporous bubbles. Pockets of gas and vapor can form and persist on flowing surfaces, and this is referred to as partial or attached cavitation. Cavitation inception occurs when cavitation is first detected in the flow as the mean pressure in the flow is reduced, and developed cavitation describes an advanced stage of cavitation, where the size of the cavity is of comparable magnitude to a characteristic flow dimension. Desinence occurs when cavitation is eliminated through an increase in the mean pressure. Cavitation is undesirable in liquid handling machinery because it may cause damage to solid surfaces, induce noise and vibrations, and lead to reduction in the mechanical efficiency. Conversely, there are useful scientific and engineering applications that employ cavitation. Comprehensive reviews of this subject can be found in Brennen (1995), Young (1989), and Franc et al. (1995).
