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|Type:||Artigo de periódico|
|Title:||Mass And Heat Transfer By High Rayleigh Number Convection In A Porous Medium Heated From Below|
|Abstract:||This paper outlines a combined theoretical and numerical study of the mass transfer effected by high Rayleigh number Bénard convection in a two-dimensional saturated porous layer heated from below. The focus of this study is on the Darcy flow, heat transfer and mass transfer scales of a single cell (roll) that exists in the steady two-dimensional convection regime. The numerical solutions are based on the complete governing equations for two-dimensional flow, and cover the Rayleigh number range 50-2000. The numerical results compare favorably with the theoretical conclusions of a scale analysis that is based on the recognition of 1. (i) two temperature difference scales in the cell, 2. (ii) a flow field without horizontal boundary layers, and 3. (iii) thermal top and bottom end-regions that are not slender enough to be boundary layers. Writing Le for the Lewis number, the overall mass transfer rate or Sherwood number is shown to scale as Le1 2Ra7 8 if Le > Ra1 4, as Le2 Ra1 2 if Ra- 1 4 < Le < Ra1 4, and as O(1) if Le < Ra- 1 4. The transition from the Darcy flow to the inertia-dominated Forschheimer flow and the scales of the Forschheimer regime are discussed in the closing section. © 1987.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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