Abstract
The mixed convection in a cubical cavity with active lateral walls and filled with a graphene-platinum hybrid nanofluid was investigated numerically and exclusively in the present paper. The lateral left and back sidewalls were kept at a hot temperature (T-h), while the lateral right and front sidewalls were kept at a cold temperature (T-c). Both the top and bottom walls were assumed thermally insulated. The top wall of the cavity was considered moving with two different directions. The first one is in the x-direction (case I), while the second case is in the z-direction (case II). Also, the case of the fixed top wall was studied just for comparison. The solid volume fractions have been varied as 0 <= phi <= 0.1%, while the Richardson number is varied in the range of 0.01 <= Ri <= 10. It was found that the maximum average Nusselt number corresponds to the case when the top wall moving in the negative x-direction. Also, the results indicated that the average Nusselt number increases with the increase in the Richardson number and the solid volume fraction.