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Diffusion enters into hydrodynamic cavitation
Prof Peter Pelz (Technische Universität Darmstadt, Chair of Fluid Systems, GE)
email: peter.pelz@fst.tu-darmstadt.de

Diffusion is said to be far too slow for being important in hydrodynamic cavitation. This general statement is wrong when it comes to the initial process of cavitation: nucleation. During nucleation there is a large velocity difference between the bulk flow and surface bounded nuclei resulting in thin diffusion layer and surprisingly high muss flux. Thus, a nucleation frequency in the order of 1 to 10 kHz is feasible. In fact, such high nucleation rate is needed for the evolution of a cavity sheet of realistic length. Diffusion cannot be ignored. It is has become the key in understanding streak, sheet and cloud cavitation