MIXED CONVECTION ANALYSIS OF HYBRID NANOFLUID IN A LID-DRIVEN CAVITY WITH A HOT BLOCK INSIDE

The purpose of this study is the investigation of heat transfer and fluid flow around a heated solid block inside a lid-driven cavity filled with hybrid TiO2-Cu/water nanofluid. The considered geometry is a two-dimensional cavity with an aspect ratio of 5. The upper wall translates with uniform velocity Ulid. The solid block attached to the bottom wall of the cavity is maintained at a high temperature compared to the temperature of the upper and lower walls, whereas the other walls are kept insulated. The hybrid nanofluid flow is assumed to be Newtonian, laminar, and incompressible. The effect of the Richardson number is considered by fixing the Reynolds number to 100, and by varying the Grashof number from 102 to 104. Volume fractions for both nanoparticles are varied from 0% to 8%. Results are shown in terms of streamlines, isotherms, and profiles of the average Nusselt number. Numerical results show that clockwise and counterclockwise cells are generated within the rectangular enclosure due to the combined effects of natural and forced convection. Furthermore, increasing the Richardson number from Ri = 0.01 to Ri = 1, which results from an increase in the buoyancy effect, leads to an increase in the Nusselt number of about 4.5%. Moreover, for each Richardson number, an increase of 8% in nanoparticles volume fraction leads to an enhancement of the heat transfer rate by about 9.8%.