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China Ocean Engineering

, Volume 32, Issue 6, pp 675–682 | Cite as

Linear Analysis of Longshore Currents Instability over Mild Slopes

  • Liang-duo Shen
  • Zhi-li Zou
  • Xi-zeng Zhao
Article
  • 15 Downloads

Abstract

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 slopes 1:100 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.

Key words

influence of bottom friction linear shear instability longshore current instability growth mode instability mode linear instability instability 

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Copyright information

© Chinese Ocean Engineering Society and Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.School of Port and Transportation EngineeringZhejiang Ocean UniversityZhoushanChina
  2. 2.State Key Laboratory of Coastal and Offshore EngineeringDalian University of TechnologyDalianChina
  3. 3.Ocean CollegeZhejiang UniversityZhoushanChina

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