This paper discusses visualizations of wave-induced flow over a rippled bed. Experiments were conducted in a wave tank fitted with a rigid rippled bed, and flow visualizations were carried out using a fluorescent dye filmed by a digital high speed video camera. Secondary flow regimes are classified in terms of key parameters such as the ripple slope, the ratio of the amplitude of the external flow to the ripple wavelength, and a Taylor number. For weak oscillations over gentle ripples, two-dimensional structures develop in the form of large recirculation cells, while for stronger flows over medium to steep ripples these are modified by the onset of separation and vortex shedding. Three-dimensional instabilities lead to disturbed-laminar flow structures of two different forms. The most common and stable form is a structure of rings that has a well-defined transverse wavelength that is found to be inversely proportional to a Taylor number. The other form, a brick pattern, is more transient in nature but is probably also related to the development of three-dimensional ripple shapes.


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    Title :

    Visualizations of the disturbed-laminar wave-induced flow above a rippled bed


    Additional title:

    Visualisierung des durch Wellen induzierten laminaren Strömungsfeldes über einem welligen Untergrund


    Contributors:

    Published in:

    Experiments in Fluids ; 36 , 6 ; 908-918


    Publication date :

    2004


    Size :

    11 Seiten, 18 Bilder, 4 Tabellen, 23 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English





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    Free access