Unsteady natural convective flow in an enclosure when there are sharp changes in side-wall temperature

Conference · Tue Jul 01 04:00:00 EDT 1997

OSTI ID:20014358

Oosthuizen, P H; Paul, J T

Natural convective flow in a square enclosure with a section of one of the vertical walls heated and with the opposite wall cooled to a uniform temperature, the remaining walls being adiabatic, has been numerically studied. The temperature of the heated wall section is constant but that of the cold wall varies, in general, in a non-periodic way with time. The main aim of the study was to determine how the nature of the temperature variation at the cooled surface influences the heat transfer rate from the hot surface. The flow has been assumed to be laminar and two-dimensional. Fluid properties have been assumed constant except for the density change with temperature that gives rise to the buoyancy forces. The governing equations have been written in dimensionless form. The resultant equations have been solved using the finite-element method. The solution has the Rayleigh number, the Prandtl number, the dimensionless size and position of the heated wall section and the form of the cold wall dimensionless temperature variation with dimensionless time as parameters. Because of the possible applications that motivated the study, results have only been obtained for a Prandtl number of 0.7. The dimensionless cold section temperature has been assumed to undergo a sharp rise in value followed a short time later by a sharp drop in its value. Results have then been obtained for modified Rayleigh numbers between 1,000 and 1,000,000 for heated wall sections of various dimensionless size and position.

• Research Organization: Queen's Univ., Kingston, Ontario (CA)
• Sponsoring Organization: Natural Sciences and Engineering Research Council of Canada
• OSTI ID: 20014358
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
CAVITIES
FINITE ELEMENT METHOD
LAMINAR FLOW
NATURAL CONVECTION
NUMERICAL ANALYSIS
SQUARE CONFIGURATION
THEORETICAL DATA
UNSTEADY FLOW
WALLS