Improvement of cavity shape modeling in water-entry of circular cylinders by considering the cavity memory effect

Abstract

Water entry is an important field in many natural, industrial and military practical applications. Several experimental and numerical studies have been conducted in order to investigate the mechanism of cavity dynamics and vortex evolution through various water entry angles of different objects. The purpose of the present research is to develop a new model to predict the cavity shape of circular cylinders at water entry stages. The proposed approach for developing the model is based on the available empirical models for the cavity radius in steady motion which is improved with consideration of the cavity memory effect for the transient stage based on Logvinovich's independence principle. In addition to the memory effect of the cavity, the effect of gravity on the axis deformation of the cavity and cavitator angle of attack are considered in developing the model. Three different cases of water entry have been considered in this paper and it is shown that the results of the proposed model are in good agreement with respect to the experimental data. The new proposed model can also predict the necking phenomenon as well as the pinch-off of the cavity with good accuracy and also the funnel shape splashes after pinching off can be observed in the results of the model.