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An experimental study of turbulent convection in air

Published online by Cambridge University Press:  29 March 2006

Daniel E. Fitzjarrald
Daniel E. Fitzjarrald
Affiliation:
Institute of Geophysics and Planetary Physics, Los Angeles, California 90024 Present address: Wave Propagation Laboratory NOAA, Boulder, Colorado.
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Abstract

An experiment was performed in a 3·5 by 3·5 m variable-height, closed convection box, with conditions ranging from a Rayleigh number of 4 × 104 up to 7 × 109, using air as the working fluid. Heat-flux measurements made at Rayleigh numbers up to 7 × 109 yielded a Nusselt number Nu = 0·13Ra0·30. Velocities and temperatures were measured up to Ra = 1·7 × 107, and Fourier spectra calculated to find the predominant horizontal scales of the motion midway between the boundaries. The predominant scale at Ra ∼ 105 was approximately four times the distance between plates, changing to six as Ra increased to 106. With side walls introduced so that the transverse aspect ratio was equal to five, Fourier spectra indicated considerable smaller scale motions, approximately equal to the layer depth. These motions decreased in size as Ra was increased. The results are discussed in relation to previous experimental and theoretical work.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 73 , Issue 4 , 24 February 1976 , pp. 693 - 719
Copyright
© 1976 Cambridge University Press

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