2011 M.Sc. Graduated Dorri Majid

Numerical Modeling of Wave Energy Dissipation by Perforated Screens

Abstract

In this thesis, Smoothed particle hydrodynamics (SPH) method is used for modeling dissipation of wave energy with horizontal perforated plate placed under water surface in a towing tank. A proposed particle neighbor search is also developed and used for reduction of simulation time. Furthermore, parallel processing is used for decreasing cast time of simulation. The proposed algorithm is faster than other algorithms in the literature. If SMP is used for parallelism of calculations, the simulation cast time decreases by increasing the number of CPU's. With use of parallel processing and the proposed particle neighbor search, the simulation cast time decreases up to 10 times using the Linked Cell List (LCL) algorithm. The simulation of dam break, wave maker, and wave reflection from a vertical wall are used to verify the parallel two dimensional code, written in C language. Variation of wave front position versus time shows a good agreement with laboratory data in the literature and with experimental data of Shao and Lo (2003). Simulation of piston wave maker shows that piston wave maker introduces regular wave perfectly. Effects of artificial viscosity, frequency, and Mach number on reflection coefficient from a vertical wall are investigated. The results show that artificial viscosity dissipates the wave energy. If artificial viscosity is used, wave reflection coefficient from the vertical wall decreases. The results show that if Goda and Suzuki (1976) method for regular wave used for calculation of wave reflection, wave reflection coefficient from the vertical wall becomes closer to laboratory data in the literature when frequency or Mach number decreases. The simulated horizontal perforated plate with forty percent porosity is located at the water surface, close to the end wall of the towing tank. Results of perforated plate modeling has compared with Cho and Kim (2008) laboratory data. Dissipation of wave energy is modeled by solving Navier-Stokes equations.