Numerical study on wave-structure interaction based on functional decomposition method

Abstract

A hybrid approach of potential and viscous flows for wave-structure interaction is developed to improve the efficiency. The total field of velocity, pressure and free surface elevation in the computational domain is decomposed into an incident field and a complementary field. For the incident wave field, the viscosity of fluid is neglected and the solution satisfies the incompressible Euler equations. With respect to the complementary field, the variables are governed by the Spectral Wave Explicit Navier-Stokes Equations (SWENSE). Furthermore, the adapted single-phase level-set model is used to capture the free surface and the dynamic structured overset technology is used to handle the large-amplitude motions of the structure. Based on this hybrid approach, an in-house code HUST-SWENSE is developed and systematic validations are carried out. The influences of the grid size, time step, wave steepness, treatment of the ship velocity and the method to obtain velocity derivatives on the regular wave propagation are first discussed in detail, along with the investigations on the performance of the HUST-SWENSE. The present method is then used to study the wave induced forces and motions for the structures with/without velocity, including a zero-velocity surface-piercing column and three ships with different velocities. Three typical ships, including the low-speed tanker ship KVLCC2 (Fr=0.142), the medium-speed container ship KCS (Fr=0.26) and the high-speed surface combatant DTMB5512 (Fr=0.41), are simulated in waves with two-degree-of-freedom (2DOF). Numerical results indicate that HUST-SWENSE is efficient and accurate for the simulation of the wave propagation and wave-structure interaction.