Abstract
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.
Original language | English (US) |
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Pages (from-to) | 395-402 |
Number of pages | 8 |
Journal | Journal of Heat Transfer |
Volume | 110 |
Issue number | 2 |
DOIs | |
State | Published - May 1988 |
Keywords
- Mixed convection
- Porous media