Mass and heat transfer by high Rayleigh number convection in a porous medium heated from below
Mass and heat transfer by high Rayleigh number convection in a porous medium heated from below
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DOI：
10.1016/0017-9310(87)90226-2
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发表时间：
1987-11
影响因子：
5.2
通讯作者：
O. V. Trevisan;A. Bejan
中科院分区：
文献类型：
--
作者：
O. V. Trevisan;A. Bejan
本文用理论和数值相结合的方法研究了高瑞利数Bénard对流对从下加热的二维饱和多孔层中的传质过程。本文研究的重点是定常二维对流中单槽(卷)的达西流动、换热和传质尺度。数值解基于完整的二维流控制方程，覆盖瑞利数范围50-2000。数值结果与基于1.(I)槽内两个温差尺度，2.(Ii)无水平边界层的流场，和3.(Iii)热的顶部和底部端部不够细而不足以作为边界层的区域的识别的尺度分析的理论结论相吻合。对于刘易斯数，总传质速率或舍伍德数按标度表示为Le 1 2Ra7 8(Le>；Ra 1 4)、Le 2Ra1 2(Ra−1 4<；Le<；Ra1 4)和O(1)(Le<；Ra−1 4)。最后一节讨论了从达西流到惯性主导的Forschheimer流的转变和Forschheimer区的尺度。
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 Le 1 2 Ra 7 8 if Le> Ra 1 4, as Le 2 Ra 1 2 if Ra− 1 4< Le< Ra 1 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.