Linear Analysis of Longshore Currents Instability over Mild Slopes  

作　　者：SHEN Liang-duo ZOU Zhi-li ZHAO Xi-zeng 

机构地区：[1]School of Port and Transportation Engineering, Zhejiang Ocean University [2]State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology [3]Ocean College, Zhejiang University

出　　处：《China Ocean Engineering》2018年第6期675-682,共8页中国海洋工程（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Grant Nos.51879237 and 11602222);the Research Fund of Zhejiang Ocean University(Grant No.11185010817);Zhejiang Provincial Natural Science Foundation of China(Grant No.LR16E090002);the Fundamental Research Funds for the Central Universities(Grant No.2018QNA4041);the Project of Research on structure properties of framed seawall along the Oujiang River in Lucheng District of Wenzhou City

摘　　要：Longshore current instability is important to nearshore hydrodynamic and sediment transport. This paper investigates the longshore current instability growth model based experimental data with different velocity profiles of slopes1:100 and 1:40 by adopting a linear shear instability model with the bottom friction effects. The results show that:(1)Only backshear mode exists in the instability of longshore current for slope 1:40 and frontshear and backshear modes may exist slope 1:100.(2) The peaks of linear instability growth mode for slope 1:100 correspond to three cases: the dominant peak is formed by the joint action of both frontshear and backshear, or by backshear alone without the existence of the smaller peak or formed by either the frontshear or backshear.(3) Bottom friction can decrease the corresponding unstable growth rate but it cannot change the unstable fluctuation period. The results of fluctuation period, wavelength and spatial variation obtained by the analysis of linear shear instability are in good agreement with experimental results.Longshore current instability is important to nearshore hydrodynamic and sediment transport. This paper investigates the longshore current instability growth model based experimental data with different velocity profiles of slopes1:100 and 1:40 by adopting a linear shear instability model with the bottom friction effects. The results show that:(1)Only backshear mode exists in the instability of longshore current for slope 1:40 and frontshear and backshear modes may exist slope 1:100.(2) The peaks of linear instability growth mode for slope 1:100 correspond to three cases: the dominant peak is formed by the joint action of both frontshear and backshear, or by backshear alone without the existence of the smaller peak or formed by either the frontshear or backshear.(3) Bottom friction can decrease the corresponding unstable growth rate but it cannot change the unstable fluctuation period. The results of fluctuation period, wavelength and spatial variation obtained by the analysis of linear shear instability are in good agreement with experimental results.

关 键 词：influence of bottom friction linear shear instability longshore current instability growth mode instability mode linear instability INSTABILITY 

分 类 号：P[天文地球]