Investigation of combined natural convection and radiation in a square enclosure with a partition

Abstract

In this research paper, the results of the numerical investigations on combined surface radiation and natural convection heat transfer in a square enclosure with partition are presented. The vertical walls of the square enclosure are differentially heated, with the left wall at a higher temperature and the right wall at a lower temperature. The partition is placed parallel to these isothermal vertical walls while the horizontal walls are adiabatic. The simulation is done for a Rayleigh Number ranging between 10³ and 10⁶, Prandtl number of 0.7 (air). In this research work, the numerical simulation is carried out using the software ANSYS FLUENT 2022R1 in which the governing equations of fluid flow and heat transfer with surface radiation are solved using finite volume-based solver and coupled algorithm. Discrete Ordinate (DO) is used as the radiation model. The thickness of the partitioned is fixed and is equal to one twentieth of the length of the square enclosure. An analysis from the obtained streamlines, temperature contours and Nusselt number values shows the significant influence of surface radiation on natural convection heat transfer. It has been observed that increasing the length of partition reduces the Nusselt number, when the height of partition is varied from h = L to L/4, the value of Nusselt number increases to 7.2% for Ra 10³ and 30.3% for Ra 10⁶. It is also established that increasing the distance of partition from hot wall increases the Nusselt number. Likewise, an increase in emissivity leads to an increase in total Nusselt number which can be noted that when emissivity is changed from 0.25 to 1, the increase in total Nusselt number is found to be 24.9% and 97.1% respectively when compared with pure convection for Ra = 10³. For Rayleigh number 10⁶ the increase in Nusselt number is 32.6% and 170.9% sequentially when compared with pure convection.