Upper and lower Rayleigh number bounds for two-dimensional natural convection over a finite horizontal surface situated in a fluid-saturated porous medium
- Texas A and M Univ., College Station, TX (United States). Dept. of Mechanical Engineering
Geothermal energy extraction has motivated fundamental research in natural convection in fluid-saturated porous media. Natural convection above a heated horizontal upward facing surface in a porous medium is one of the many fundamental problems being studied in geothermal heat transfer. A numerical study is presented of natural convection from a heated upward facing finite horizontal surface in a fluid-saturated porous medium. The Rayleigh number range for which two-dimensional flows occur is numerically determined as 40 {le} Ra {le} 600. At higher Rayleigh numbers the flow is shown to become three-dimensional with multiple plume formation and growth. At lower Rayleigh numbers the transport is dominated by conduction, and there is greater uncertainty in the numerical determination of heat transfer rates by convection models. For the two-dimensional flows the correlation for the Nusselt number is obtained as Nu = 3.092Ra{sup 0.272}. The fundamental physical mechanisms of convection in a vast porous medium are presented and explained with the aid of the numerical results.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 624313
- Journal Information:
- Numerical Heat Transfer. Part A, Applications, Journal Name: Numerical Heat Transfer. Part A, Applications Journal Issue: 5 Vol. 33; ISSN 1040-7782; ISSN NHAAES
- Country of Publication:
- United States
- Language:
- English
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