LATTICE BOLTZMANN ANALYSIS OF MIXED CONVECTION IN A LID-DRIVEN CAVITY WITH AN INNER HOT ELLIPTICAL BLOCK: EFFECT OF BLOCK INCLINATION

Abstract

This study is a computational analysis of hydrodynamic and thermal behavior of combined natural and forced convection with a moving wall in a square enclosure containing an elliptical block. This inner block is exposed to a hot temperature. The enclosure is full of air which is cooled on its side walls by a low temperature. The remaining surfaces are thermally insulated, and the upper surface is sliding at a steady speed <i>u</i>₀. In particular, the impact of various factors related to geometry, such as the emplacement and the elliptical block inclination are analyzed for the range of the dimensionless parameter Richardson number (0.01 &le; Ri &le; 100) by using lattice Boltzmann method (LBM) with single relaxation time model (SRT). LBM offers the advantage of handling irregular geometries and curved boundaries without requiring complex mesh generation, simplifying computations, and reducing computational costs in comparison to the traditional methods. The findings are in the forms of streamlines, temperature contours, the mean Nusselt number, and the fluid mean temperature inside the enclosure. The results show that for the prevailing natural convection and for the centrally placed elliptical block, the dynamic and thermal fields are almost indicated by symmetry with regard to the mid-vertical of the enclosure. Moreover, the inclination of the elliptical block prevents the enhancement of the heat transfer for all positions of the block; except when the block is located close to the upper surface, the inclination improves the rate of heat transfer especially for Ri &le; 1.