Isentropic one-fluid modelling of unsteady cavitating flow

Unlike attached cavitation, where the cavitation boundary is steady or changes relatively slowly and periodically, the cavitation such as that observed in an underwater explosion consists of a dynamically developing boundary and can evolve to a certain dimension before collapsing very violently. The development and collapse of such cavitation is sustained mainly by the pressure jump across the cavitation boundary. In this work, the focus is on developing a one-fluid model for such cavitating flows. After the analysis and discussion are carried out for some existing one-fluid cavitation models, such as Vacuum model, Cut-off model and Schmidt's model, a mathematically more consistent one-fluid model is then developed to study the creation, evolution and collapse of such unsteady cavitation by assuming that the cavitating flow is a homogeneous mixture of isentropic gas and liquid components. In the model, both the ambient water and the mixture of cavitating flow are taken as compressible. Besides the theoretical analysis, the present model is also tested against various problems with either exact solution, or experimental data or comparison to other existing models, and then applied to a 3D underwater problem in a cylinder.