In this paper, three-dimensional free-surface flows are simulated by using two different numerical methods, CIP(constrained interpolation profile)-based and FV(finite volume)-based methods. In the CIP-based method, the Euler equation is solved on stationary staggered Cartesian grids by a finite difference method, and an immersed boundary technique is applied to deal with wave-body interactions. In the FV-based method, the governing equations are solved by applying collocated finite volume discretization, and body-fitted meshes are used. Free-surface boundary is considered as the interface of multi-phase flow with air and water, and a volume-of-fluid (VOF) approach is applied to trace free surface. Among many variations of VOF-type method, the tangent of hyperbola for interface capturing (THINC) and compressive interface capturing scheme for arbitrary meshes (CICSAM) techniques are used in the CIP-base method and FV-based method, respectively. Numerical simulations have been carried out for dam-breaking and wave-body interaction problems. The computational results of the two methods are compared with experimental data and their differences are observed.
Wave-body interaction problems are important for the design of ships and offshore structures. Potential-based codes give reasonable results for engineering purpose. However, they have some limitations to simulate strongly nonlinear wave-body interaction flows. Among alternative approaches, direct numerical methods based on the Navier- Stokes or Euler equations are getting popular, thanks to the dramatic increase of computational resources. Yang and Löehner (2006) also showed highly nonlinear wave-body interaction simulations such as slamming and green water using VOF, FEM, and suggested efficient extrapolation algorithm. Hu et al. (2008) showed some threedimensional computations of strongly nonlinear wave-ship interaction problems by using CIP method. Monroy et al. (2009) presented the Reynolds Averaged Navier-Stokes (RANS) simulations of ship motions in regular and irregular head seas, cooperating with potential based incident waves.
