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Experimental non-Boussinesq fountains

Published online by Cambridge University Press:  09 November 2015

Rabah Mehaddi ,
Olivier Vauquelin  and
Fabien Candelier
Rabah Mehaddi*
Affiliation:
Aix-Marseille Université, Laboratoire IUSTI, UMR CNRS 7343, 5 rue Enrico Fermi, 13 453 Marseille, CEDEX 13, France
Olivier Vauquelin
Affiliation:
Aix-Marseille Université, Laboratoire IUSTI, UMR CNRS 7343, 5 rue Enrico Fermi, 13 453 Marseille, CEDEX 13, France
Fabien Candelier
Affiliation:
Aix-Marseille Université, Laboratoire IUSTI, UMR CNRS 7343, 5 rue Enrico Fermi, 13 453 Marseille, CEDEX 13, France
*
†Email address for correspondence: [email protected]
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Abstract

Laboratory experiments involving downward air–helium fountains are presented. The large density differences between these releases and the ambient allow us to investigate how non-Boussinesq effects modify fountain heights and fountain fluctuations in comparison with the Boussinesq case (i.e. marginal density differences). In these experiments, the source Froude number is varied over a wide range covering (i) the very weak, (ii) the weak and (iii) the forced fountain regimes. It is shown that the classical Boussinesq correlations can be extended to the non-Boussinesq case provided that the Froude number is multiplied by the square root of the ratio between the released fluid density and that of the ambient. In the range investigated, no influence of the source Reynolds number is observed.

JFM classification

Convection: Convection Convection: Plumes/thermals
Type
Rapids
Information
Journal of Fluid Mechanics , Volume 784 , 10 December 2015 , R6
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Copyright
© 2015 Cambridge University Press 

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