Numerical simulation of MHD free convection in a two-dimensional trapezoidal cavity of a hybrid nanofluid has been carried out in this research. The cavity is heated sinusoidal from the bottom wall, and the inclined walls are cooled while the top wall is isolated. The hybrid nanofluid (MgO-Ag/water) has been used as a working fluid. The numerical simulation has been validated with past papers and met a good agreement. The considered parameters are a range of Rayleigh number (Ra= 103 to 106), Hartmann number (Ha= 0 to 60) and volume fraction (f= 0 to 0.02). The results are presented as isotherms, stream functions, local and average Nusselt numbers, from which it is observed that the strength of the stream functions and isotherms increases with the increase of the Ra and ϕ while the increase in Hartmann number reduce the circulation of the flow and increases the isotherms strength. Also, the Nusselt number is increases with Ra and ϕ while it decreases with Ha.
Ferrofluid is a one-of-a-kind substance that functions both as a magnetic solid and as a liquid. In this article, waterbased Fe3O4 and Mn-ZnFe2O4 nanofluids between parallel stretchable spinning discs are considered. To carry out the study, the influence of rotational viscosity in the flow, which is due to the difference in rotation between the fluid and magnetic particles, and the applied magnetic field are examined. Additional impacts incorporated to the novelty of the model are the variable viscosity and variable thermal conductivity. The Legendre-based collocation method (LBCM) is used to solve the set of governing equations. To ensure the code validity, a comparison with analytical results is conducted and an excellent consensus is accomplished. Comparisons of the pertinent parameters on the flow profiles are displayed in tabular and graphical forms. Analyses reveal that the ferromagnetic Fe3O4 nanofluid shows higher thermal conductivity strength than the ferromagnetic Mn-ZnFe2O4 nanoparticles. This study finds its usefulness in aerospace, biotechnology, medical sciences, material sciences, and so on.
The present study investigates mixed convective and fluid flow characteristics in a lid-driven enclosure filled with air and its walls subjected to various heating conditions. The vertical (left and right) walls of the enclosure are cooled (Tc), and the bottom wall is heated to (Th) while the horizontal lid-driven upper wall is subjected to sinusoidal heating. The dimensionless governing equations (continuity, momentum, and energy transport) were implemented in COMSOL Multiphysics 5.4 software. The influences of Grashof number (103 ⩽ Gr ⩽ 105
) and Reynold number in the interval of 1 ⩽
Re
⩽ 100 on the average Nusselt number ( NU ) for all walls of the cavity was examined. Furthermore, the results presented in the form of isotherms, streamlines, and the local and average Nusselt numbers in the enclosure for
Re ⩽ 100 and
Gr
in the range of 103
⩽
Gr
⩽ 105
. The results indicated the highest and lowest average rate of heat transfer at the bottom and top walls of the cavity respectively. The top wall region presented a higher velocity as confirmed by the velocity contour plots.
The impacts of MHD and heat generation/absorption on lid‐driven convective fluid flow occasioned by a lid‐driven square enclosure housing an elliptic cylinder have been investigated numerically. The elliptic cylinder and the horizontal enclosure boundaries were insulated and the left vertical lid‐driven wall was experienced at a fixed hot temperature, and the right wall was exposed to a fixed cold temperature. COMSOL Multiphysics 5.6 software was used to resolve the nondimensional equations governing flow physics. A set of parameters, such as Hartmann number (0
≤
italicHa
≤
50 $0\le {Ha}\le 50$), Reynolds number (1
0
2
≤
italicRe
≤
1
0
3 $1{0}^{2}\le {Re}\le 1{0}^{3}$), Grashof number (1
0
2
≤
italicGr
≤
1
0
5 $1{0}^{2}\le {Gr}\le 1{0}^{5}$), heat generation‐absorption parameter (−
3
≤
J
≤
3 $-3\le J\le 3$), and elliptical cylinder aspect ratio (AR) (1.0
≤
italicAR
≤
3.0 $1.0\le {AR}\le 3.0$) have been investigated. The current study discovered that for low Reynolds number, the adiabatic cylinder AR of 2.0 provided the optimum heat transfer enhancement for the model investigated, also the impact of cylinder size diminishes beyond Gr = 104. But for high Reynolds (Re = 1000), the size of the cylinder with AR = 3.0 offered the highest heat transfer augmentation. The clockwise flow circulation reduces because of an increase in AR, which hinders the flow circulation. In addition, heat absorption supports heat transfer augmentation while heat generation can suppress heat transfer improvement.
The purpose of this paper is to numerically investigate the effects of some geometric parameters and flow variables on heat transfer augmentation in annuli with equi-spaced internal longitudinal fins along the external walls. A fully developed flow and a constant thermal boundary condition of uniform heat flux at the walls of the pipe were assumed. Continuity, momentum and energy transport equations were adopted for the solutions of the problem. A Q-BASIC code was written based on the finite difference scheme generated. Numerical experiments were conducted to ascertain the effects of Reynolds number Re, radius ratio, R.R, Prandtl number Pr, fin height H, and pipe inclination, on the rate of heat transfer and fluid flow. The results obtained show that for 50 ≤ Re ≤ 500, total Nusselt number NuT increases with increase in Re while for Re > 500, there was no significant increase in NuT. Nusselt number, average velocity and bulk temperature of the fluid increase with increasingin the range 0° ≤ ≤ 75° but for the range 75°≤ ≤ 90° the effect is negligible. For R.R > 0.6, the heat transfer was observed to be almost independent of R; therefore for economic purposes, heat exchangers similar to the configuration studied should be run at a low pumping power. A numerical study was done to validate the program by test running it for the finless annuli for similar boundary conditions; the results obtained in the present work show the same trend as that of Kakac and Yucel.
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