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This study examines the magnetohydrodynamic flow of hybrid silver-alumina (Ag-Al 2 O 3 )/water nanofluid within a corrugated trapezoidal cavity that contains a heat-generating rotating solid cylinder. The hybrid nanofluid flow and convective heat transfer are modelled using a single-phase approach. The governing equations for fluid flow and convective heat transfer are solved using the penalty finite element method. The finite element algorithm was validated against previously published work, and it was found to be in good agreement with the existing literature. We investigate the effects of the Ag and Al 2 O 3 nanoparticle diameters and the radius of the heat-generating solid cylinder on streamlines, isotherms and average Nusselt number. The results of this study reveal that the flow circulation regions near the rotating cylinder are enhanced with increased nanoparticle diameters and cylinder radius. Moreover, the nanofluid temperature and heat transfer rate are increased with reduced nanoparticle diameters and increased cylinder radius. [ABSTRACT FROM AUTHOR]

The present work elucidates the hydrothermal characteristics within a non-Darcian porous complex wavy enclosure saturated with Al 2 O 3 –Cu– H 2 O hybrid nanofluid considering a uniform magnetic field. The left sidewall of the enclosure is wavy and heated isothermally, whereas the other sidewall is maintained at ambient temperature, all other walls are insulated. The Forchheimer–Brinkman-extended Darcy model is implemented to analyze the flow through porous media. The dimensionless transport equations are numerically solved following the finite volume-based in-house computational code with successive staggered non-uniform mesh distribution. The hydrothermal behaviors are investigated meticulously changing the dimensionless variables like undulation amplitude (λ ), Hartmann number (Ha), Darcy number (Da), and modified-Rayleigh number ( Ra m ). The remarkable results reveal that enhancing the heating surface area by heightening the amplitude of the undulation always leads to higher heat transfer, but does not always favor the growth of the flow strength. The heightening of the flow strength with amplitude is noted for higher Ra m only. The flow intensity, as well as heat transfer, increases with the growing Ra m . The same decreases with increasing Da and Ha. Local distribution of heat transfer characteristics shows complex behavior depending on the amplitude of the undulations and associated dimensionless numbers. [ABSTRACT FROM AUTHOR]

A numerical study was conducted to determine the impact of MHD on mixed convection of a Cu-water nanofluid in a horizontal channel attached to two open enclosures filled with a porous material is implemented in this paper. Uniform heat is supplied on the base of the two enclosures while the other walls are considered adiabatic. The finite element method has been utilized in this study to solve the considered equations and other numerical simulations that needed to be validated, assessed with previous papers to ensure that the model works correctly. Furthermore, this study considers a range of each of the Reynolds number (Re = 25, 50, 100, 150, 200), Richardson number (Ri = 0.1, 1, 3, 5, 8, 10) and the Hartmann number (Ha = 0, 5, 10, 15, 30, 50) at a constant volume fraction ( φ = 0.08) and porous media properties (Da = 10-2, and ε = 0.7). The results stated that the strength of the streamlines, isotherms, and the average Nusselt number (Nu avg ) increases with increasing values of the Richardson and Reynolds numbers while they decrease upon increasing the Hartmann number. The result shows that no big difference between cases 2 and 3, and the maximum enhancement in Nu avg is 9.84% in case 2 compared with case 1 at Re = 200, Ri = 1, and Ha = 0. [ABSTRACT FROM AUTHOR]

In this study, natural laminar convection of Al 2 O 3 /water nanofluid in a cavity slightly different from shaped H was investigated using the monophasic model. The various parameters of this flow were determined numerically using CFD-Fluent software using the finite-volume method by introducing Boussinesq approximation. The analysis is carried out for three values of the Rayleigh number (10 5 ; 2.3 · 10 5 and 3.072 · 10 5) and for three values of the form factor defined for this enclosure (0.2; 0.3 and 0.4). The impact of Rayleigh number, nanofluid concentration and cavity form factor on dynamic and thermal structure of the flow was analyzed. The results are shown in form of streamlines, isotherms, and profiles of velocity, temperature, and Nusselt number. Nusselt number rises with increasing Rayleigh number and nanofluid concentration and decreases with the form factor of the cavity. This study is well developed relative to those carried out before. With using Al 2 O 3 nanofluid, the heat transfer is improved because its thermal conductivity is increased compared to that of the base fluid. Finally, to predict heat transfer inside cavity, correlations for the Nusselt number were proposed for each form factor of the cavity. These correlations are rarely presented in this type of study. [ABSTRACT FROM AUTHOR]