Accurate finite volume investigation of nanofluid mixed convection in two-sided lid driven cavity including discrete heat sources

In the present work, two-dimensional mixed convection fluid flow and heat transfer of water–(Cu, Ag, Al2O3 and TiO2) nanofluids in a two-sided facing lid-driven cavity partially heated from below have been investigated numerically. Two discrete heat sources are located on the bottom wall of the enclosure; however, the vertical moving walls and the ceiling are cooled at constant temperature. The remaining boundary parts of the bottom wall are kept insulated. The flow is driven by the moving two facing vertical walls in the same direction and the buoyancy force. The governing equations are solved using a second order accurate finite volume approach. The effects of the monitoring parameters in given ranges such as Reynolds (1⩽Re⩽100)(1⩽Re⩽100) and Richardson numbers (1⩽Ri⩽20)(1⩽Ri⩽20), solid volume fraction (0⩽φ⩽0.2)(0⩽φ⩽0.2), the nanoparticles materials as well as the two heat sources positions are investigated. The conducted benchmark study leads to excellent accordance with previous findings. The present study analyzes and discusses the flow patterns (streamlines structures and isotherms distributions) set up by the competition between the forced flow driven by the moving walls and the buoyancy force effects, and the heat transfer rate quantified by the averaged Nusselt number along the heat source. It was found that significant heat transfer enhancement can be obtained: (i) increasing Ri at high Reynolds number (Re = 100) results in up-to 20% augmentation of heat transfer rate for all Cu volume fractions; (ii) increasing the volume fraction φ, a maximum heat transfer rate increase of 47.010% is reached with Cu suspensions for φ = 0.2 and Ri = 1, while a minimum increase of 7.059% is observed for TiO2-water nanofluid at Ri = 10 and φ = 0.05; (iii) a highest heat transfer enhancement occurs when heat sources move toward the two vertical moving walls, while a lower heat transfer is obtained for heat sources located at bottom wall center.