Natural convection heat transfer performance of non-newtonian power-law fluids enclosed in cavity with complex-wavy surfaces

Numerical simulations are performed to investigate the natural convection heat transfer performance of non-Newtonian power-law fluids in a cavity bounded by wavy vertical walls with different temperatures and flat horizontal walls under adiabatic conditions. The results show that for Rayleigh numbers greater than 103, the mean Nusselt number has a significantly increase as the flow behavior index is decreased. Moreover, it is shown that in the convection-dominated regime, the mean Nusselt number increases with an increasing Rayleigh number, while in the conduction-dominated regime, the mean Nusselt number remains approximately constant. Finally, it is shown that for a given fluid, the heat transfer performance can be optimized via an appropriate tuning of the wavelength and amplitude of the wavy surface depending on the Rayleigh number.