Turbulent oscillating channel flow subjected to a free-surface stress.

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Kramer, W. and Clercx, H.J.H. and Armenio, V. (2010) Turbulent oscillating channel flow subjected to a free-surface stress. Physics of Fluids , 22 (9). 095101. ISSN 1070-6631

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Abstract:The channel flow subjected to a wind stress at the free surface and an oscillating pressure gradient is investigated using large-eddy simulations. The orientation of the surface stress is parallel with the oscillating pressure gradient and a purely pulsating mean flow develops. The Reynolds number is typically Re$_\omega$ = 10^6 and the Keulegan–Carpenter number—the ratio between the oscillation period and advection time scale—is KC=80. Results compare favorably to the data from direct numerical simulations obtained over a single period. A slowly pulsating mean flow occurs with the turbulent flow essentially being statistically steady. Logarithmic boundary layers are present at both the bottom wall and the free surface. Turbulent streaks are observed in the bottom and free-surface layer. The viscous sublayer below the free surface is, however, much thinner. This observation is verified by simulations we performed for a purely wind-driven channel flow. For the oscillating flow, additional low-speed splats localized regions of upwelling occur at the free surface when the mean velocity and stress are in the same direction.
Item Type:Article
Copyright:© 2010 American Institute of Physics
Faculty:
Electrical Engineering, Mathematics and Computer Science (EEMCS)
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Link to this item:http://purl.utwente.nl/publications/75847
Official URL:http://dx.doi.org/10.1063/1.3481149
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