Characterization of natural convection and entropy generation within a circular baffle inside two connected inclined square cavities filled with a Cu-Al 2 O 3 -hybrid nanofluid under thermal radiation

Enhancing thermal performance and lowering heat loss in energy conversion systems are essential, especially for new and complicated products that make this requirement worse. In order to address this difficulty, this study looks at fluid flow and heat transmission using hybrid nanofluid and nanoporous materials in combination cavities. The numerical simulation of natural convection within a hollow two-dimensional cavity comprised of two connected tilted squares with a circular hollow at the center is investigated. The inner heated square is filled with a nanoporous material, whereas the rest of the cavity is filled with Cu-Al 2 O 3 hybrid nanofluid. The COMSOL Multiphysics software is utilized to simulate the dimensionless governing equations. A comparison with previously published research showed a good agreement. Calculations are performed for different values of Ra number (Ra: 10 3 , 10 4 , 10 5 , and 10 6 ), Darcy number (Da: 10 –1 , 10 –2 , 10 –3 , 10 –4 , and 10 –5 ), volume fraction ( φ : 0, 0.02, 0.04, and 0.06), width ( W : 0, 0.1, 0.2, 0.3, and 0.4), and uniform porosity ( ε : 0.2, 0.4, 0.6, and 0.8). The results demonstrated that the increase of the porosity leads to a decrease in the Nu number with the Rayleigh number increase. Darcy and Rayleigh numbers have a significant impact on the width ( W ) between the hybrid nanofluid and nanoporous layers. In addition to the above, the fluid flow slows down at Ra = 10 3 , which causes Ṡ_gen,0.5em⌣T and Be to increase. The rising of Ra from 10 4 to 10 5 causes no change in the Ṡ_gen,0.5em⌣T because heat is primarily transported by conduction, but the maximum Be number is reduced.