Cavitation modelling

Cavitation modelling is a type of computational fluid dynamic (CFD) that represents the flow of fluid during cavitation. It covers a wide range of applications, such as pumps, water turbines, pump inducers, and fuel cavitation in orifices as commonly encountered in fuel injection systems. Cavitation modelling is a type of computational fluid dynamic (CFD) that represents the flow of fluid during cavitation. It covers a wide range of applications, such as pumps, water turbines, pump inducers, and fuel cavitation in orifices as commonly encountered in fuel injection systems. Modelling efforts can be divided into two broad categories: vapor transport models and discrete bubble models. Vapor transport models are best suited to large-scale cavitation, like sheet cavitation that often occurs on rudders and propellers. These models include two-way interactions between the phases. The discrete bubble model includes the effects of the surrounding fluid on the bubbles. Discrete bubble models, e.g. the Rayleigh-Plesset, Gilmore and Keller-Miksis, describe the relation between the external pressure, bubble radius and the velocity and acceleration of the bubble wall. Two-phase modeling is the modelling of the two phases, as in a free surface code. Two common types of two phase models are homogeneous mixture models and sharp interface models. The difference between both the models is in the treatment of the contents of cells containing both phases. Most recent cavitation modelling efforts have used homogeneous mixture models, in which the contents of individual cells are assumed to be uniform. This approach is best suited to modeling large numbers of bubbles that are much smaller than one cell. The disadvantage of this approach is that when the cavities are larger than one cell, the vapor fraction is diffused across neighboring cells by the vapor transport model. This is different from the sharp interface models in that the vapor and liquid are modeled as distinct phases separated by an interface. In sharp interface models, the interface is not diffused by advection. The model maintains a sharp interface. Naturally, this is only appropriate when the bubble size is at least on the order of a few cells. Phase change models represent the mass transfer between the phases. In cavitation, pressure is responsible for the mass transfer between liquid and vapor phases. This is in contrast to boiling, in which the temperature causes the phase change. There are two general categories of phase change models used for cavitation: the barotropic models and equilibrium models. This section will briefly discuss the advantages and disadvantages of each type.