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An experimental investigation of convection in a fluid that exhibits phase change

Published online by Cambridge University Press:  20 April 2006

D. E. Fitzjarrald
Affiliation:
Department of Land, Air and Water Resources, University of California, Davis, CA 95616 Current affiliation: Geophysical Fluid Dynamics Institute, Florida State University, Tallahassee, Florida 32306.

Abstract

Convection flows have been systematically observed in a layer of fluid between two isothermal horizontal boundaries. The working fluid was a nematic liquid crystal, which exhibits a liquid–liquid phase change at which latent heat is released and the density changed. In addition to ordinary Rayleigh–Bénard convection when either phase is present alone, there exist two distinct types of convective motions initiated by the unstable density difference. When a thin layer of heavy fluid is present near the top boundary, hexagons with downgoing centres exist with no imposed thermal gradient. When a thin layer of light fluid is brought on near the lower boundary, the hexagons have upshooting centres. In both cases, the motions are kept going once they are initiated by the instability due to release of latent heat. Relation of the results to applicable theories is discussed.

Type
Research Article
Copyright
© 1981 Cambridge University Press

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