Numerical studies are reported for steady, mixed convection in two-dimensional horizontal porous layers with localized heating from below. The interaction mechanism between the forced flow and the buoyant effects is examined for wide ranges of Rayleigh number Ra* and Peclet number Pe*. The external flow significantly perturbs the buoyancy-induced temperature and flow fields when Pe* is increased beyond unity. For a fixed Peclet number, an increase in Rayleigh number produces multicellular recirculating flows in a domain close to the heat source. This enhances heat transfer by free convection. However, for a fixed Ra*, an increase in forced flow or Peclet number does not necessarily increase the heat transfer rate. Hence, there exists a critical Peclet number as a function of Ra* for which the overall Nusselt number is minimum. The heat transfer is, generally, dominated by the buoyant flows for Pe* < 1 whereas the contribution of free convection is small for Pe* > 10 when Ra* ≤ 10.
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Mixed Convection in Horizontal Porous Layers Heated From Below
V. Prasad,
V. Prasad
Department of Mechanical Engineering, Columbia University, New York, NY 10027
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F.-C. Lai,
F.-C. Lai
Department of Mechanical and Aerospace Engineering, University of Delaware, Newark, DE 19716
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F. A. Kulacki
F. A. Kulacki
Department of Mechanical and Aerospace Engineering, University of Delaware, Newark, DE 19716
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V. Prasad
Department of Mechanical Engineering, Columbia University, New York, NY 10027
F.-C. Lai
Department of Mechanical and Aerospace Engineering, University of Delaware, Newark, DE 19716
F. A. Kulacki
Department of Mechanical and Aerospace Engineering, University of Delaware, Newark, DE 19716
J. Heat Transfer. May 1988, 110(2): 395-402 (8 pages)
Published Online: May 1, 1988
Article history
Received:
March 7, 1987
Online:
October 20, 2009
Citation
Prasad, V., Lai, F., and Kulacki, F. A. (May 1, 1988). "Mixed Convection in Horizontal Porous Layers Heated From Below." ASME. J. Heat Transfer. May 1988; 110(2): 395–402. https://doi.org/10.1115/1.3250498
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