Open Access

ARTICLE

Influence of Layer Height on Thermal Buoyancy Convection in A System with Two Superposed Fluids Confined in A Parallelepipedic Cavity

by Sunil Punjabi¹, K. Muralidhar², P. K. Panigrahi²

1 Corresponding Author: Postdoc fellow, School of Mechanical Engg., Tel Aviv University, 69978 Tel Aviv Israel. E-mail:sunil@eng.tau.ac.il.
2 Department of Mechanical Engineering, Indian Institute of Technology (I.I.T), Kanpur 208016 India

Fluid Dynamics & Materials Processing 2006, 2(2), 95-106. https://doi.org/10.3970/fdmp.2006.002.095

Abstract

Convection in a differentially heated two-layer system consisting of air and water was studied experimentally, using laser-interferometry. The cavity used for flow visualization was square in cross-section and rectangular in-plan having dimensions of 447 × 32 × 32 mm³. Experiments performed over different layer thicknesses of water filled in a square cross-section cavity, the rest being air, are reported in the present work. The following temperature differences for each layer height were imposed across the hot and the cold walls of the superposed fluid layers: (i) ΔT=10K and (ii)ΔT =18 K. The present study was aimed at understanding the following issues: (a) the influence of Rayleigh number on the steady thermal field, and (b) flow coupling mechanisms between the layers. Experiments show that the thermal field in the fluid layers is primarily determined by the temperature difference and hence the Rayleigh number. In the thicker water layer (1/3 air - 2/3 water) case, with increase in Rayleigh number, the no-coupling mode changes into a thermal coupling mode. For the equal layer heights (1/2 air - 1/2 water) case, the two-layers are thermally coupled at a lower Rayleigh number, while the mechanical and thermal coupling both become significant at higher Rayleigh number. Also, for the thicker air layer (2/3 air - 1/3 water) case, a full or joint coupling (mechanical + thermal) was observed for all the Rayleigh numbers obtained in the experiment.

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