ABSTRAKT

Natural convection of a nanofluid (NF) consisting of water and (Ag or TiO₂) in an inclined enclosure cavity has been studied numerically; the left and right walls of the cavity have a complex-wavy geometry and are maintained at a low and high temperature (random temperature, based on the random function), respectively. Meanwhile, the upper and lower walls of the cavity are both flat and insulated. The governing equations are solved numerically using the finite volume. The complex-wavy-surface is modeled as the superimposition of two sinusoidal function approaches. Results are presented in the form of streamlines, isotherms, and average Nusselt number. In addition, a parametric study is carried out to examine explicitly the volume fraction effects of nanoparticles (NPs) (φ = 0.1, 0.2), the Rayleigh number (Ra = 10³,10⁴, 10⁵), the inclination angle of the cavity (γ = 0°, 45°, 90°, 135°, 180°), types of temperature (constant, random), types of NF (Ag and TiO₂), and the complex-wavy-surface configuration. The results reveal that NPs addition remarkably enhances heat transfer in the cavity, especially for φ = 0.2. Besides, the effect of inclination angle and type of temperature is more pronounced at higher Rayleigh number. Moreover, it is shown that the heat transfer performance can be optimized by tuning the wavy-surface geometry parameters.