Numerical Modelling Of Flow And Local Scour Around A Vertical Cylinder

When a pile is placed in water, the presence of the pile will change the flow pattern in its neighborhood, resulting in the following phenomena: strength of the flow turbulence around the pile, the contraction of the flow, the formation of a horseshoe vortex in front of the pile and lee-wake shedding. These are the agent for scour around the pile. The scour will influence the steady of the offshore structures, threatening the safety of the structures. It will cost a lot protecting the offshore structures from scour. Based on this background, this paper uses numerical method to study the flow field and scour around the pile.Flow around bottom-mounted pile has been studied for many years, but few of literatures consider the influence of turbulent model and Froude number on the flow field. Computation of flow field is divided into two parts: one is comparison of turbulent model, and the other is influence of Froude number on the free surface. The calculation results are validated against experimental data. Some flow information like velocity, pressure, separation angle for lee-wake vortices are analyzed in this thesis. At present multiphase flow model is a hot topic. Eulerian model, one of multiphase flow model, is used to simulate local scour around the pile. In the model, collisions between particles, gravity and drag force are taken into account.