Mixed convection heat transfer performance of water-based nanofluids in lid-driven cavity with wavy surfaces

A numerical investigation is performed into the mixed convection heat transfer characteristics of water-based nanofluids confined within a lid-driven cavity. In modeling the cavity, it is assumed that the left and right walls have a wavy surface, while the upper and lower walls are both flat. In addition, it is assumed that the left wavy-wall has a constant heat flux, the right wavy-wall is maintained at a low temperature, and the upper and lower walls are both insulated and move horizontally. The analysis considers three different nanofluids, namely Cu-water, Al₂O₃-water and TiO ₂-water. In performing the analysis, the governing equations are modeled using the Boussinesq approximation and are solved numerically using the finite-volume method. The simulations focus on the respective effects of the nanoparticle volume fraction, the type of nanofluid, the Richardson number, the Grashof number and the wavy surface geometry parameters on the mean Nusselt number. The results show that for all considered values of the Richardson number, the mean Nusselt number increases with an increasing volume fraction of nanoparticles. In addition, it is shown that the Cu-water nanofluid yields the best heat transfer performance of the three nanofluids. Furthermore, it is shown that the mean Nusselt number increases with an increasing Grashof number given a constant Richardson number. Finally, the results show that for a given nanofluid, the mean Nusselt number can be optimized via an appropriate tuning of the wavy surface geometry parameters.