Numerical and experimental studies of natural convection in a heated cavity with a horizontal fin on a hot sidewall

Abstract

This study presents a hybrid method of inverse method and three-dimensional computational fluid dynamics (CFD) commercial software along with various flow models and experimental data to investigate natural convection in a heated cavity with a horizontal fin on a hot sidewall. The effect of fin position and initial temperature on the results obtained is investigated. First, the inverse method of the finite difference method along with the experimental temperature data is used to estimate the heat transfer coefficient on the heating fin. Afterwards, the CFD along with various flow models and the inverse results of the obtained heat transfer coefficient is used to determine the air temperature and velocity profiles, the fin surface temperature and the heat transfer coefficient on the fins. More accurate results and appropriate flow model and grid points can be obtained if the resulting heat transfer coefficient and fin temperature are as close as possible to the inverse results and the experimental temperature measurements, respectively. The results show that the zero-equation turbulence model is more suitable for this problem than other flow models. More grid points may not necessarily get more accurate results. The present results are new findings and are different from previous 2D results. The heat transfer coefficients on the upper and lower surfaces of the fin can be different and vary with the position of the fin. The average heat transfer coefficient at the 35 mm fin position is 1.70 times that of the 85 mm fin position. An interesting finding is that the vortices at upper two corners of the cavity and near the upper surface of the fin edge vary with fin position. This means that the influence of fin position on the flow field cannot be ignored. The proposed correlation between Nusselt number and Rayleigh number well matches the inverse and numerical results obtained.