Effect of walls motion direction on mixed convection heat transfer in a double lid-driven square enclosure with an embedded hot cylinder: A lattice Boltzmann method study

Abstract

This computational investigation explores the effect of wall motion direction on mixed convection heat transfer in a double sliding walls square cavity including a centric hot elliptical cylinder (block). The left and right vertical walls of the cavity maintain a cold temperature, while the top and bottom walls are thermally insulated and slide at uniform velocity. The analysis employs the lattice Boltzmann method using the single relaxation time approximation. Two scenarios of walls motion direction, namely same direction and opposite direction, are considered. The impact of aspect ratio (AR = 0.5, 1, and 2) and solid-to-fluid volume fraction (χ = 10%, 20%, and 30%) of the inner cylinder are examined across a broad spectrum of Richardson numbers (0.01 ≤ Ri ≤ 100). The examination is conducted for both scenarios of walls velocity direction. The findings demonstrate that the rate of heat transfer and fluid temperature are notably influenced by the direction of walls motion, aspect ratio, solid-to-fluid volume fraction of the cylinder, and Richardson number. Moreover, the heat transfer rate exhibits a considerable increase in the same direction scenario compared to the opposite direction at AR = 0.5 and AR = 1, whereas the opposite trend is observed for AR = 2, particularly at lower values of Ri. These results offer valuable insights for optimizing heat transfer performance in analogous enclosed systems.