Numerical Investigation Of Solitary Wave Interaction With Group Of Cylinders

Abstract

A numerical model is developed to solve the three dimensional wavestructure interaction problem. This model is based on the filtered Navier-Stokes equations or Eulers equation for incompressible flow. A two-step projection finite volume scheme is adopted to solve the N-S equations and the free surface movement is tracked by the piecewise linear volume of fluid (VOF) method. The large eddy sub-grid model is used for the turbulence calculation. In the large eddy simulation (LES), the small scale eddies are modeled by the sub-grid scale model, and the large eddies are explicitly solved. Traditional Smagorinsky LES model and RNG LES model are implemented in this study. The numerical model has been validated by using non-breaking waves. Non-breaking solitary wave or periodic Stokes wave propagating in a constant water depth are numerically simulated. The numerical solutions are compared with the analytical theory or laboratory measurements. The conservative property of the numerical model is also inspected. In general, the numerical model gives satisfactory results for the wave kinematics, such as the free surface displacement, phase speed and fluid velocity. The numerical model is then used to simulate solitary waves and their interaction with a group of slender vertical piles in a constant water depth. The Eulers equation is numerically solved since the waves are non-breaking. The numerical results are compared with laboratory data in terms of free surface displacements, fluid particle velocity and wave forces. The relatively less satisfactory agreement is observed in the dynamic pressure on the cylinder, but this could be due to the measurement errors. The complex three-dimensional flow patterns, the velocity and pressure fields are presented and discussed. Later, the breaking solitary waves on a slanted beach and their interaction with a slender cylinder are studied. The large eddy simulation (LES) is used for the turbulence calculation. The numerical results show reasonably good agreements with the laboratory data. Discussion about the choice of LES subgrid model is also presented.