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The steady and unsteady backwash vortices

Published online by Cambridge University Press:  20 April 2006

N. Matsunaga
Affiliation:
Department of Civil Engineering Hydraulics and Soil Mechanics, Kyushu University, Fukuoka 812, Japan
H. Honji
Affiliation:
Research Institute for Applied Mechanics, Kyushu University, Fukuoka 812, Japan

Abstract

A circulatory flow called a ‘backwash vortex’ forms under waves running up a sloping bed. The backwash vortex is classified into two types: the ‘steady backwash vortex’ and the ‘unsteady backwash vortex’. The former is a steady streaming formed when Re2 < 90, and the latter an unsteady separated flow formed when Re2 > 90, where Re2 is a form of Reynolds number. The ratio of the lengthscale of the backwash vortex to the swash length is proportional to Re2−½ when Re2 [Lt ] 30, and becomes constant when Re2 is sufficiently large.

Type
Research Article
Copyright
© 1983 Cambridge University Press

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References

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