Visualizations of the disturbed-laminar wave-induced flow above a rippled bed
Visualizations of the disturbed-laminar wave-induced flow above a rippled bed
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 which 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.
908-918
Ourmières, Y.
a41f365b-59ec-42e8-a6ba-12704bd34cff
Chaplin, J.R.
d5ed2ba9-df16-4a19-ab9d-32da7883309f
August 2004
Ourmières, Y.
a41f365b-59ec-42e8-a6ba-12704bd34cff
Chaplin, J.R.
d5ed2ba9-df16-4a19-ab9d-32da7883309f
Ourmières, Y. and Chaplin, J.R.
(2004)
Visualizations of the disturbed-laminar wave-induced flow above a rippled bed.
Experiments in Fluids, 36 (6), .
(doi:10.1007/s00348-003-0774-y).
Abstract
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 which 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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Published date: August 2004
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Local EPrints ID: 53801
URI: http://eprints.soton.ac.uk/id/eprint/53801
ISSN: 0723-4864
PURE UUID: e79d3a13-d559-4961-8c1c-b20b6bc4ee33
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Date deposited: 22 Jul 2008
Last modified: 16 Mar 2024 03:13
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Y. Ourmières
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