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The offshore vortex train

Published online by Cambridge University Press:  26 April 2006

N. Matsunaga ,
K. Takehara  and
Y. Awaya
N. Matsunaga
Affiliation:
Department of Earth System Science and Technology, Kyushu University, Kasuga-shi 816, Japan
K. Takehara
Affiliation:
Department of Civil Engineering, Kinki University, Osaka 577, Japan
Y. Awaya
Affiliation:
Department of Land and Water Development, Kyushu-Kyoritsu University, Kitakyushu-shi 807, Japan
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Abstract

A row of two-dimensional vortices forms in an offshore zone when regular surface waves run up a sloping flat bed. This vortex row is called the offshore vortex train. The vortices begin to appear near the breaking point. Moving in the offshore direction, they develop and increase their horizontal lengthscale through vortex merging. After reaching a particular offshore location, however, they decay rapidly. The formation region of the vortex train has been investigated on the basis of visual experiments for three bed slopes. Its formation does not depend on the type of wave breaking but is observed when the steepness of deep-water waves is smaller than 4.2 × 10−2. The horizontal lengthscale of the vortices and the velocities of the vortex movement have also been evaluated empirically.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 276 , 10 October 1994 , pp. 113 - 124
Copyright
© 1994 Cambridge University Press

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