Damping of gravity–capillary waves on the surface of turbulent fluid

Investigation of damping of gravity–capillary waves (GCW) on the surface of turbulent fluid is a classical problem which geophysical applications are related to the problems of swell damping, interpretation of radar and optical images of ship wakes, development of physical mechanisms of wind wave su...

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Veröffentlicht in:Experiments in fluids 2020, Vol.61 (8), Article 184
Hauptverfasser: Shomina, Olga, Kapustin, Ivan, Ermakov, Stanislav
Format: Artikel
Sprache:eng
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Zusammenfassung:Investigation of damping of gravity–capillary waves (GCW) on the surface of turbulent fluid is a classical problem which geophysical applications are related to the problems of swell damping, interpretation of radar and optical images of ship wakes, development of physical mechanisms of wind wave suppression, etc. Analysis of the relevant literature reveals the necessity of setting reliable experiments to study the effect of damping of GCW due to turbulence. An original laboratory method of investigation of surface wave damping due to turbulence is described. The method is based on the parametric excitation of standing surface waves (so-called Faraday ripples) and simultaneous and independent generation of turbulence. The wave damping coefficient is determined by a threshold acceleration corresponding to the surface wave parametric excitation. The disadvantages of the previously used methods are eliminated or significantly reduced in the presented method, and the results are formulated in terms of eddy viscosity. It is revealed that the eddy viscosity coefficient is proportional to the rms velocity of turbulent pulsations, and achieves a maximum as a function of GCW frequency, when the GCW wavelengths are of order of the scales of turbulent eddies. This effect has never been mentioned in the literature, since the previous studies were focused on the investigation of wave damping due to small-scale (relative to the GCW wavelengths) turbulence. Applications of the obtained results to real-sea conditions are discussed. Graphic abstract
ISSN:0723-4864
1432-1114
DOI:10.1007/s00348-020-03022-5