A Numerical Study Of Mixed Convective Heat Transfer From Narrow Side-Up Two-Sided Isothermal Flat Plates

Abstract

Many studies of mixed convective heat transfer from heated flat plates which are in the same plane as the forced flow over the plate surface are available, most of these studies dealing with wide plates. However, there exist practical situations in which there is mixed convection from thin two-sided plates that lie in a vertical plane in a horizontal forced flow, the plate thus being at right angles to the forced flow. In some such cases the plates are also narrow, and the relative plate width is expected to have a significant influence on the heat transfer rate in such a case. The present study therefore numerically investigates how the relative width of the plate affects the mixed convective heat transfer rate from a thin narrow side-up rectangular plate. It has been assumed that the plate surfaces are isothermal and at the same temperature. The Boussinesq approach has been adopted. Conditions under which laminar, transitional, and turbulent flows exist have been considered, the standard k-epsilon turbulence model being used with buoyancy force effects being accounted for. The solution has been obtained using ANSYS FLUENT © . The mean heat transfer rates from the surfaces of the plate have been expressed in terms of Nusselt numbers based on the length of the plate. These Nusselt numbers are dependent on the Rayleigh number and the Reynolds number based on the plate length, on the ratio of the plate width to the plate length, and on the Prandtl number. Results have only been obtained for a Prandtl number of 0.74. Variations of the Nusselt numbers with Rayleigh number and with Reynolds number for various dimensionless plate widths have been obtained. The results show that the effect of the plate width can be very significant.