Application of multiphase Riemann-SPH in analysis of air-cushion effect and slamming load in water entry

Abstract

The impact of structure on water is an important and practical issue in ocean engineering. For some cases, the influence of air on the impact characteristics is non-negligible. In particular, when the flat-bottomed structure impacts on water such as the emergency landing on the water of an aircraft and helicopter, the air cushion will be formed which buffers the impact of the structure, thereby reducing its slamming load. In this paper, considering the advantages of the Riemann solver in dealing with discontinuities, a multiphase Riemann-SPH method using the PVRS Riemann solver is applied to analyze the air-cushion effect and slamming load in water entry problems. To reduce the numerical dissipation led by the Riemann solver, a dissipation limiter for the PVRS Riemann solver is given. Through the test of the water slamming of the plate, the accuracy and convergence of the adopted method are firstly validated. Then, the influences of the air cushion and the plate length on the slamming load are discussed. Finally, a complex engineering problem, i.e., the slamming of the LNG tank insulation panel is simulated, and the influences of the impact velocity and deadrise angle on slamming load characteristics are analyzed.