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Effect of Rayleigh numbers on the evolution of double-diffusive salt fingers

Singh, OP and Srinivasan, J (2014) Effect of Rayleigh numbers on the evolution of double-diffusive salt fingers. In: PHYSICS OF FLUIDS, 26 (6).

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Official URL: http://dx.doi.org/ 10.1063/1.4882264


This is a transient two-dimensional numerical study of double-diffusive salt fingers in a two-layer heat-salt system for a wide range of initial density stability ratio (R-rho 0) and thermal Rayleigh numbers (Ra-T similar to 10(3) - 10(11)). Salt fingers have been studied for several decades now, but several perplexing features of this rich and complex system remain unexplained. The work in question studies this problem and shows the morphological variation in fingers from low to high thermal Rayleigh numbers, which have been missed by the previous investigators. Considerable variations in convective structures and evolution pattern were observed in the range of Ra-T used in the simulation. Evolution of salt fingers was studied by monitoring the finger structures, kinetic energy, vertical profiles, velocity fields, and transient variation of R-rho(t). The results show that large scale convection that limits the finger length was observed only at high Rayleigh numbers. The transition from nonlinear to linear convection occurs at about Ra-T similar to 10(8). Contrary to the popular notion, R-rho(t) first decrease during diffusion before the onset time and then increase when convection begins at the interface. Decrease in R-rho(t) is substantial at low Ra-T and it decreases even below unity resulting in overturning of the system. Interestingly, all the finger system passes through the same state before the onset of convection irrespective of Rayleigh number and density stability ratio of the system. (C) 2014 AIP Publishing LLC.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the AMER INST PHYSICS, CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA
Department/Centre: Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited: 10 Oct 2014 09:13
Last Modified: 10 Oct 2014 09:13
URI: http://eprints.iisc.ac.in/id/eprint/49988

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