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 faisal_durr February 11, 2011 07:16

Speed of Hot air Rising

Hi guys, Im carrying out salt bath experiments. My case consists of a hot plume rising in an empty room. Can anyone tell me what formula to use to find out the speed of the hot plume rising? Thanks.

 chrisjcoffey February 11, 2011 09:41

The centre-line velocity in the buoyant plume behaves like
W~B^(1/3)z^(-1/2),
where B is the buoyancy flux and z the vertical coordinate.

The classic paper "Morton, B. R., Taylor, G. I. & Turner, J. S. 1956 Turbulent gravitational convection from maintained and instantaneous sources. Proc. Roy. Soc. A 234, 1–23." provides derivations of the velocity in a buoyant plume. Alternatively, the book "Fischer, H. B., List, E. J., Koh, R. C. Y., Imberger, J. & Brooks, N. H. 1979 Mixing in Inland and Coastal Waters. Academic Press, Inc." provides a good derivation from a dimensional analysis view point.

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