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Wave boundary layers in a convergent tunnel
AbstractThis work deals with turbulent oscillatory boundary layers in a convergent-divergent channel with smooth walls. Two kinds of measurements were conducted: velocity measurements and wall shear-stress measurements. Most of the measurements were conducted for three different values of the half-angle of divergence β, namely 0°, 0.5° and 1°. Two other parameters which govern the flow are the Reynolds number, Re, and the parameter where a is the amplitude of water particles at the center of the channel and D is the half-width of the channel. In the tests Re was maintained constant, approximately at Re=6×106, while was varied over a range from about 20 to 39 in most of the experiments.The results indicate that there exists a constant streaming near the wall in the direction towards the convergent end of the channel. The magnitude of this streaming increases with β and also with the distance from the divergent end of the channel. The results further indicate that the friction coefficient increases with β for the convergent half period and decreases with it for the divergent half period. Regarding the turbulence, the experiments show that turbulence is largely suppressed in the convergent half period; this is felt even in the early stage of the following divergent half period. It recovers, however, shortly after and an immense growth in turbulence is observed for the rest of the divergent half period of the flow.
Wave boundary layers in a convergent tunnel
AbstractThis work deals with turbulent oscillatory boundary layers in a convergent-divergent channel with smooth walls. Two kinds of measurements were conducted: velocity measurements and wall shear-stress measurements. Most of the measurements were conducted for three different values of the half-angle of divergence β, namely 0°, 0.5° and 1°. Two other parameters which govern the flow are the Reynolds number, Re, and the parameter where a is the amplitude of water particles at the center of the channel and D is the half-width of the channel. In the tests Re was maintained constant, approximately at Re=6×106, while was varied over a range from about 20 to 39 in most of the experiments.The results indicate that there exists a constant streaming near the wall in the direction towards the convergent end of the channel. The magnitude of this streaming increases with β and also with the distance from the divergent end of the channel. The results further indicate that the friction coefficient increases with β for the convergent half period and decreases with it for the divergent half period. Regarding the turbulence, the experiments show that turbulence is largely suppressed in the convergent half period; this is felt even in the early stage of the following divergent half period. It recovers, however, shortly after and an immense growth in turbulence is observed for the rest of the divergent half period of the flow.
Wave boundary layers in a convergent tunnel
Sumer, B.M. (Autor:in) / Laursen, T.S. (Autor:in) / Fredsøe, J. (Autor:in)
Coastal Engineering ; 20 ; 317-342
03.06.1993
26 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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