A sharp interface multiphase flow model for two-dimensional water impact of a symmetric and asymmetric wedge

Abstract

A Cartesian grid based sharp interface (SI) multiphase flow model is developed to investigate the symmetric and asymmetric impact of a wedge with sharp phase changes. A level set based ghost fluid method (GFM) with formal second-order accuracy is incorporated to maintain the jump properties across the two-phase interface with transient phase change. The arbitrary moving boundaries and free surfaces are handled by a radial basis function ghost cell method (RBFGCM) and a gradient augmented level set (GALS) method, respectively. The water impact of a symmetric wedge is simulated to demonstrate the accuracy and capability of the present SI method by comparing the present peak pressures with the experimental data. Also, satisfactory convergences of the grid size and the time step are obtained. Then, the symmetric and asymmetric water impact with different deadrise and inclination angles is investigated by the present SI model and the diffused interface (DI) model. The present SI model is demonstrated to perform well for various deadrise and inclination angles, except the nearly flat plate slamming. By contrast, the diffuse interface (DI) model can obtain reasonable solution for the relative impact angle no less than 15o. However, the peak pressure is considerably underestimated and its occurring moment lags behind the experimental data for a smaller impact angle, which is severer for a smaller impact angle. In addition, we analyzed the variation rules of the impulsive pressure, the motion response, the pressure distribution, and the free surface motion with respect to the relative impact angle. The maximum fluid force grows acceleratingly as the relative impact angle decreases, while the duration is shortened. Also, some typical impact phenomena are observed such as flow separation, jet flow, and ventilation for a small impact angle.