The coincidence of two events leads to the cavitation inception: the sufficient pressure drop and the occurrence of the cavitation nuclei. The most important feature of the inception phenomenon is that both of the mentioned factors may have the features of random events. In case of turbulent flow around a screw propeller blade the pressure at the bubble surface neighbourhood and bubbles' radius should be described by the random variables. Consequently the course of the bubble radius variation is described by a realisation of certain stochastic process. The essence of the cavitation inception model presented in the following paper is the investigation of influence of random pressure field on the cavitation nuclei and bubbles. The bubble (nuclei) radius is examined instead of its trajectory. The origin of the frame of reference in which the spherical bubble is considered coincides always with its centre. The 'observer' placed inside the bubble can recognise that the cavitation begins on the base of knowledge about the external pressure without any information about his actual location in the flow field. The fundamental objective of the proposed stochastic model is the possibility of prediction of the cavitation inception probability in unsteady, turbulent flow. The model can be applied for the analysis of the cavitation inception in the flow around screw propeller blade.
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