Journal of Fluid Mechanics

Papers

Laboratory observations of mean flows under surface gravity waves

S. G. MONISMITHa1a4, E. A. COWENa2, H. M. NEPFa3, J. MAGNAUDETa4 and L. THAISa5

a1 Environmental Fluid Mechanics Laboratory, Stanford University Stanford, CA 94305-4020, USA

a2 Department of Civil and Environmental Engineering Cornell University, Ithaca, NY 14853, USA

a3 Parsons Laboratory, MIT, Cambridge MA 02139, USA

a4 Institut de Mécanique des Fluides de Toulouse, UMR-CNRS-INPT-UPS 5502, Toulouse 31400, France

a5 Laboratoire de Mécanique de Lille, UMR-CNRS 8107, Polytech'Lille, Université de Lille I, Villeneuve D'Ascq, Cedex 59655, France

Abstract

In this paper we present mean velocity distributions measured in several different wave flumes. The flows shown involve different types of mechanical wavemakers, channels of differing sizes, and two different end conditions. In all cases, when surface waves, nominally deep-water Stokes waves, are generated, counterflowing Eulerian flows appear that act to cancel locally, i.e. not in an integral sense, the mass transport associated with the Stokes drift. No existing theory of wave–current interactions explains this behaviour, although it is symptomatic of Gerstner waves, rotational waves that are exact solutions to the Euler equations. In shallow water (kH ≈ 1), this cancellation of the Stokes drift does not hold, suggesting that interactions between wave motions and the bottom boundary layer may also come into play.

(Received October 21 2005)

(Revised August 02 2006)

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