Dynamics of a tail cavity induced by the vertical motion of an underwater vehicle

This study investigates the dynamics of the tail cavity induced by an underwater vehicle. The morphological evolution and pressure characteristics of the tail cavity are simulated using a numerical model based on the boundary integral method. The numerical model is validated against tail cavity experiments conducted by us. The mechanisms of certain tail cavity behaviors during the cavity evolution process are explored from the perspective of pressure, and the pressure characteristics of the flow field at different vertical and radial positions are obtained. Then, the influence of the initial vehicle velocity and the initial cavity pressure parameter on cavity fracture and cavity jet are studied. In terms of the fracture behavior, we find that the fracture location of the tail cavity and the length of the sub-cavities undergo abrupt changes as the initial vehicle velocity and cavity pressure parameter vary. The secondary necking of the tail cavity is considered as the primary cause of these abrupt changes. In terms of the jetting behavior, we find that the governing parameters impact the collapse extent of the sub-cavities at the moment of jet impact. Finally, the variation characteristics of the jet kinetic energy of the attached sub-cavity and the residual sub-cavity at this moment are quantitatively studied within the selected parameter space.