Double-diffusive natural convection in a vertical porous annulus

Journal Article · Fri Aug 13 04:00:00 EDT 1999 · Numerical Heat Transfer. Part A, Applications

OSTI ID:687452

Beji, H; Bennacer, R; Duval, R ^[1]; Vasseur, P ^[2]

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1. Lab. Materiaux et Sciences des Constructions, Neuville sur Oise (France)
2. Univ. of Montreal, Quebec (Canada). Ecole Polytechnique

Double-diffusive convection in porous media has been extensively investigated in recent years, owing to its relevance in varied applications. Examples include the dispersion of chemical contaminants through water-saturated soil, the migration of moisture through the air contained in fibrous insulation and grain-storage installations, and the exploitation of continental geothermal reservoirs. Here, a numerical study is carried out on double-diffusive natural convection in a vertical annular porous layer whose vertical walls are at constant temperatures and concentrations. The investigation covers the range 10 {le} R{sub T} {le} 500, 1 {le} Le {le} 10, {minus}50 {le} N {le} 50, 1 {le}A {le} 5, 1 {le} {kappa} {le} 10, where R{sub T}, Le, N, A, and {kappa} are the thermal Rayleigh number, Lewis number, buoyancy ratio, aspect ratio, and radius ratio of the enclosure, respectively. The two extreme cases of heat-driven and solute-driven natural convection correlations, valid in the boundary layer regime, are derived to calculate the average Nusselt and Sherwood numbers in terms of the governing parameters of the problem. In order to investigate the effects of the combined thermal and solutal buoyancy forces on the average heat and mass transfer, results have been obtained for a large range of buoyancy ratios N. Streamlines, isotherms, and isosolutes in the system are produced to illustrate the flow structure transition from mass species dominated opposing to thermal dominated and mass species dominated aiding flows, respectively. The thermal Rayleigh and Lewis numbers and the radius ratio are found to influence the buoyancy ratio at which flow transition and flow reversal occurs.

• OSTI ID: 687452
• Journal Information: Numerical Heat Transfer. Part A, Applications, Journal Name: Numerical Heat Transfer. Part A, Applications Journal Issue: 2 Vol. 36; ISSN 1040-7782; ISSN NHAAES
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
ANNULAR SPACE
ENVIRONMENTAL TRANSPORT
GEOTHERMAL SYSTEMS
NATURAL CONVECTION
NUMERICAL ANALYSIS
POROUS MATERIALS
THERMAL INSULATION