Numerical Simulation of Diffracted Wave by Vertical Cylinder Using VOF Method

Abstract

This paper presents numerical simulations of a diffracted wave around a bottom-mounted circular cylinder using the volume-of-fluid (VOF) method. Unsteady incompressible Navier-Stokes equations are solved based on the finite volume method (FVM) with a collocated variable arrangement. The SIMPLE-type correction algorithm with the momentum interpolation method is applied to solve Poisson equations. Among the many variations of the VOF method is the CICSAM (Compressive Interface Capturing Scheme for Arbitrary Meshes) scheme. To verify the availability in 2-phase flow simulations of the developed numerical code, dam-breaking and sloshing problems are investigated. The simulation results show good agreement with existing experiments in both flow pattern and global force. Before the numerical simulation of 3D diffraction problems, the wave is tested in a numerical wave tank. In this study, we introduce a buffer zone for efficient wave-making and damping; in the buffer zone, the near-field solution is gradually changed to the known incident wave at the far field. Second-order Stokes waves are well simulated in this wave tank. Finally, a diffracted wave by vertical circular cylinders is numerically simulated. The wave-induced forces and run-ups around the cylinder are compared with potential flow solutions based on the finite element method (FEM). Agreement between the 2 numerical solutions is fairly good.