tThis study presents the effect of nanofluid on mixed convection heat transfer inside a liddriven cavity by 2D and 3D numerical simulations. The 3D simulation is performed to exam-ine the accuracy of 2D simulation for mixed convection. Two phase mixture model has beenused for simulating the nanofluid. The effect of Brownian motion is considered in deter-mining the effective thermal conductivity of nanofluid. The Richardson number changesfrom 0.1 to 10. In addition, thin fins have been mounted on hot wall to augment the heattransfer. Results indicate that there is a secondary flow at moderate and high Richardsonnumbers that 2D simulation cannot predict it. Also, results indicate that 2D simulation over-estimated the enhancement of heat transfer at high concentration of nanofluid. Simulationdepicts that heat transfer increases by adding low concentration of nano-particles and itdecreases with higher concentrations. Adding fins on hot surface increases the heat trans-fer only at high Richardson number. Fins cannot enhance convective heat transfer at lowand moderate Richardson numbers due to a blockage of flow at corners of the fins.
