On Turbulent Characteristics and Numerical Simulation of 2-Dimensional Sub-Breaking Waves

Abstract

The purpose of the present paper is to simulate numerically the 2-dimensional sub-breaking waves which are generated by a submerged hydrofoil. Experimental investigations are carried out first to find out a turbulence model by relating the turbulence quantities to the averaged velocity. Then the numerical simulation is carried out by solving the Reynolds-averaged equations with a turbulence model.
The experimental results showed that the flow fields near the wave crest where the sub-breaking is appearing have velocity defects and are similar to those in the turbulent boundary layer developed on the solid surface. The free-surface boundary condition is investigated including the Reynolds stress. A 0-equation turbulence model is proposed as the simplest model. The k-equation model is modified under the assumption that the turbulence intensity is almost isotropic.
Numerical simulations of sub-breaking waves are carried out by making use of both the O-equation and the k-equation models under the free-surface boundary condition where the Reynolds stress components are taken into account. Through the comparisons with the measured data, it is found that the inclusion of the Reynolds stress terms is important.