Improved prediction of 3-D water entry with a CIP method and parallel computing

Abstract

This paper presents the further development of a constrained interpolation profile (CIP) based method to solve highly non-linear 3-D slamming problems with a parallel computing algorithm and an improved interface capturing scheme. The water entry problems, governed by the Navier-Stokes (N-S) equations, were treated as multi-phase problems (solid, water and air) and solved by the fractional step method, in which the 3-D CIP method was employed for the advection phase and a pressure-based algorithm was applied to the non-advection phase. The interfaces between different phases were captured by using density functions. The advection of the water phase was solved by applying the THINC/WLIC scheme, i.e., tangent of hyperbola for interface capturing with weighted line interface calculation. A six-degree-of-freedom (6DOF) motion solver was developed to simulate the free fall water entry. A Message Passing Interface (MPI) parallel computing scheme was implemented by decomposing the computational domain. The speed-up performance was investigated. Validation studies were carried out for the water entry of a 3-D wedge with prescribed velocities. The free fall water entry of a modified Wigley hull and an inclined circular cylinder was also studied. The computed slamming forces and motions were compared with experimental results and other published numerical results.