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The response of a turbulent boundary layer to abrupt changes in surface conditions

Published online by Cambridge University Press:  28 March 2006

A. A. Townsend
A. A. Townsend
Affiliation:
Emmanuel College, Cambridge
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Abstract

In a previous paper, it was shown that abrupt changes in the surface conditions under a very deep boundary layer cause changes of mean velocity and temperature that satisfy the dynamical conditions for self-preserving development. Here the theory is extended to predict the development of the modified flow in the moderately deep layers that occur in nature and the laboratory. The problems considered are the changes in the velocity profile produced by an abrupt change of surface roughness and also by a line of concentrated roughness such as a fence, the changes in temperature produced by change of roughness combined with changes of heat flux at the surface, and diffusion of heat or a scalar pollutant from a line source at or near ground level. The predictions are compared with observations by Rider (1952) of the flow downwind of a hedge, by Rider, Philip & Bradley (1963) of temperature and humidity downwind of a change in surface, and of vertical diffusion from a line-source at ground level.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 22 , Issue 4 , August 1965 , pp. 799 - 822
Copyright
© 1965 Cambridge University Press

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References

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