Efficient Simulation of Fully Coupled Wave-body Interactions Using a Sharp Interface Immersed-boundary/level-set Method

In this paper, some recent progress toward the prediction of fully coupled wave-body interactions using a sharp interface immersed-boundary/level-set method is presented. A noniterative strong coupling scheme for the fluid motion and rigid body dynamics is adopted by utilizing a non-inertial reference frame attached to the solid body. The combination of this scheme with the previous immersed-boundary/level-set method gives a robust and efficient tool for the prediction of solid body motions in waves. Several examples are presented to demonstrate the applicability of the new method. Possible further developments are discussed. INTRODUCTION Wave-body interactions are of interest in many engineering areas such as ocean, coastal, civil, and environmental engineering. The physics involved in wave-body interactions, e.g., multiphase turbulent flows of wind, current, and waves, dynamics of stationary/moving solid/deformable structures, and the interactions between the fluids and structures, is very complicated and presents significant challenges to theoretical, experimental, and computational studies of these phenomena. Ship hydrodynamics is a typical field with a focus on wavebody interactions. The prediction of ship motions is the primary task of computational ship hydrodynamics, since ship motions are ubiquitous in all major areas of ship hydrodynamics, ∗Address all correspondence to this author. such as sinkage and trim in resistance and propulsion, pitch, heave, and roll in seakeeping, surge, sway, and yaw in maneuvering. Potential flow theory has been applied to ship motion prediction for a long time. However, the missing viscous effects and limited capacities for breaking waves in various potential flow solvers severely restrict their broader applications. RANS (Reynolds-averaged Navier-Stokes) solvers of various complexities have been developed in the last few decades for ship hydrodynamics problems beyond the reach of general potential solvers. CFDShip-Iowa version 4 is one of leading RANS codes for a wide range of ship hydrodynamics applications involving six DOF (degree-of-freedom) motions [1]. Unfortunately, these solvers usually require complicated three-dimensional (3D) mesh generation/deformation, block patching, or overset interpolation, which are absent in general potential flow solvers and practically excessive burdens on design engineers. The sharp interface immersed-boundary/level-set Cartesian grid method presented in [2], among other non-boundary-conforming methods, can essentially eliminate the complex grid generation process and be a promising approach for simple and efficient prediction of ship motions. In this method, the direct forcing immersed boundary formulation for moving boundary problems given in [3] was adopted; in addition, a level set method [4] was used for interface tracking with the ghost fluid method for the treatment of interface jump conditions [5]. Various cases of wave-body interactions with stationary or moving bodies from water entry and exit, to model scale ship flows were shown in [2] to demonstrate the accuracy and applicability of this method. 1 Copyright c © 2010 by ASME Proceedings of the ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting and 8th International Conference on Nanochannels, Microchannels, and Minichannels FEDSM-ICNMM2010 August 1-5, 2010, Montreal, Canada