Numerical simulation of bed shear stress in swash zone

• Main Authors: Chien-yehHo, 何建業
• Other Authors: Hwung-Hweng Hwung
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/19167847707032824333

碩士 === 國立成功大學 === 水利及海洋工程學系碩博士班 === 101 === In this study, the dynamic process of solitary wave propagating from shore to swash zone is investigated numerically by using a 2-D Reynolds Averaged Navier-Stokes (RANS) solver. The turbulence field is described by using a non-linear k-ε turbulence closure model and the free surface configuration is tracked by the Volume Of Fluid (VOF) method. To validate the numerical model, the results were compared with theoretical solution and existing experimental data. The result of the validation shows good agreement. Besides, the numerical model is applied to investigate the horizontal velocity, bottom shear stress, turbulence kinetic energy (TKE) and boundary layer in the swash zone of the different bed roughness and bed slopes. The results show that the maximum velocity, bottom shear stress and turbulence kinetic energy exerted by uprush, and the maximum bottom shear stress and turbulence kinetic energy increase with the bed roughness and bed slope increase. The maximum velocity decreases as the bed roughness increase, but increases with the bed slope increases. The boundary layer vanishes during flow reversal and then grows during the backwash, and becomes depth limited at the end of the swash cycle. From the analysis of the velocity and turbulence field, the boundary layer flow was observed obviously as the bed roughness increases. When the bed slope increases the solitary wave in the form of spilling breaker to surging breaker.