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Valley ventilation by cross winds

Published online by Cambridge University Press:  19 April 2006

Robert C. Bell  and
Rory O. R. Y. Thompson
Robert C. Bell
Affiliation:
C.S.I.R.O. Division of Atmospheric Physics, P.O. Box 77, Mordialloc, Victoria, Australia 3195
Rory O. R. Y. Thompson
Affiliation:
C.S.I.R.O. Division of Atmospheric Physics, P.O. Box 77, Mordialloc, Victoria, Australia 3195
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Abstract

An initial thermal stratification may be swept out of a valley if a cross-wind is strong enough: the valley is then said to be ventilated. Numerical and laboratory experiments indicate that the critical parameter is the Froude number, , where is the mean horizontal velocity above the crest of the valley sides, N is the Brunt–Väisälä or bouyancy frequency of the thermal stratification in the valley air and h is the height of the valley walls. Ventilation occurs whenever the Froude number exceeds a value of 1·3.

Information

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 96 , Issue 4 , 27 February 1980 , pp. 757 - 767
Copyright
Copyright © 1980 Cambridge University Press

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Footnotes

*

Present address: C.S.I.R.O. Division of Fisheries and Oceanography, P.O. Box 21, Cronulla, N.S.W., Australia, 2230.

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