Internal wave generation in Flow3D model

Abstract

For the internal wave generation in the Navier-Stokes equation model using the VOF scheme, Lin and Liu (1999) developed an internal wavemaker method for which a mass source function of the continuity equation was used to generate target wave trains. Also, Choi and Yoon (2009) developed the internal wave generation scheme using momentum source to produce the target waves, which is applied to the RANS equation model in a CFD code, FLUENT. In this study, two approaches including mass source and mass flux methods were devised for the application in a CFD code, FLOW-3D. Also, the sponge layer scheme using the porous media was introduced to remove the reflected waves into the computational area as proposed by Choi and Yoon (2009). The achieved results were compared to the analytical solutions of the Airy theory, Stokes' 2nd order and Stokes' 5th order theory. Also, the self-adaptive wave generator was devised to produce the accurate mass flux according the changes of the surface elevation in which the vertical profile of horizontal particle velocities are changed based on the position of free surface. This method will be expanded to the application of short waves, which the vertical particle velocities are more important for the accurate generation of free surface than that in case of long wave. The comparisons between the numerical results and the analytical solutions showed the good agreements not only the free surface elevation but the vertical profile of horizontal particle velocities. This achievement can be applied to the 3 dimensional wave simulations such as the wave tranquility study in the harbor area and the wave propagation from the offshore to the nearshore. Copyright © 2011 by the International Society of Offshore and Polar Engineers (ISOPE).