Setting up a numerical flume using a hybrid particle-mesh method

A literature survey which concerns a variety of wave generation and absorption methods was accomplished. The survey deals with the methods used for the experiment wave tank and numerical wave tank. Their implementations are also described very briefly. The numerical wave tank (NWT) was set up using the hybrid particle-mesh method with the emphasis on the wave generation of solitary wave and linear progressive wave, and passive absorption at the far side of the wave tank. The Discontinuous Galerkin method was applied to solve the Navier-Stokes equations on the background mesh while the particles are used for solving the non-linear advection term. The waves are generated by using a piston-type wavemaker with the use of first-order linear wavemaker theory. For the absorption of reflected waves at the termination end, the sponge layer approach was implemented making use of viscous damping or internal friction among water particles. The hyperbolic tangent function is found to be applicable for smoothly increasing viscosity in the damping zone, which is also be able to prevent the formation of rigid body at the transition point. The drawbacks of the passive absorption technique are not only the extra cost of computational power and domain size, but also the rising slope of average water surface elevation induced by the accumulation of water particles near the end of the wave tank. The solitary waves of small amplitude could be simulated with reliable accuracy and also did the linear progressive waves in the intermediate water. The short waves and the long waves need to paid more attention for the wave generation boundary condition. Regarding the passive absorption for both of solitary waves and progressive waves, the same hyperbolic tangent function was used for viscosity functions which increases spatially. The solitary wave can be damped out using this function while the latter one cannot be damped, leading to the instability of the computation induced by the loss of the particles in the mesh system.Civil Engineering and GeosciencesHydraulic Engineerin