Title: Bed Shear Stress And Turbulence Characteristics Under Solitary Waves
by Prof. Pengzhi Lin (林鹏智)
Co-author: Haijiang Liu, Dandan Chen, Fang He, Xiaochun Tang and Xizeng Zhao
Bottom friction under waves is of fundamental importance to understand sediment transport and bed morphology in coastal waters. The friction characteristics are strongly related to turbulence initiated from bottom and broken free surface. Many of previously studies adopted simplified approaches by neglecting the realistic transient properties of friction. The aim of the present study is to find the bottom friction dependency on near bottom velocity and acceleration, the latter of which represents the flow unsteadiness but was not adequately investigated before. A series of laboratory experiments were conducted in flumes to measure the velocity, turbulence, and bed shear stress under various types of waves. In a mean time, a numerical model was also developed by using the BSL turbulence model for simulation of detailed flow and turbulence structures in and outside of the wave-induced turbulence boundary layers. The experimental data and numerical results will be used to help us understand the time-varying bottom friction features in surf zones.