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Unsteady hydromagnetic mixed convection of a radiating and reacting nanofluid in a microchannel with variable properties

Kefene Mesfin Zewde, Makinde Oluwole Daniel, Enyadene Lemi Guta

Engineering Transactions

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2023

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Vol. 71, iss. 1

53--79

EN

Unsteady MHD mixed convection of nanofluid heat transfer in a permeable microchannel with temperature-dependent fluid properties is studied under the influence of a first-order chemical reaction and thermal radiation. The viscosity and thermal conductivity are assumed to be related to temperature exponentially. Using suitable dimensionless variables and parameters, the governing partial differential equations (PDEs) are transformed to their corresponding dimensionless forms solved numerically by a semi-discretization finite difference scheme along with the Runge-Kutta-Fehlberg integration technique. The effects of model parameters on the profiles of velocity, temperature, concentration, skin friction, the Nusselt number, and the Sherwood number are discussed qualitatively with the aid of graph.

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Natural and mixed convection of a nanofluid in porous cavities: critical analysis using buongiorno’s model

Zahmatkesh Iman, Habibi Mohammad Reza

Journal of Theoretical and Applied Mechanics

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2019

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Vol. 57 nr 1

221--233

EN

In this paper, Buongiorno’s mathematical model is adopted to simulate both natural convection and mixed convection of a nanofluid in square porous cavities. The model takes into account the Brownian diffusion and thermophoresis effects. Both constant and variable temperatures are prescribed at the side walls while the remaining walls are maintained adiabatic. Moreover, all boundaries are assumed to be impermeable to the base fluid and the nanoparticles. The governing equations are transformed to a form of dimensionless equations and then solved numerically using the finite-volume method. Thereafter, effects of the Brownian diffusion parameter, the thermophoresis number, and the buoyancy ratio on the flow strength and the average Nusselt number as well as distributions of isocontours of the stream function, temperature, and nanoparticles fraction are presented and discussed.

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Unsteady three-dimensional MHD nanofluid flow over a stretching sheet with variable wall thickness and slip effects

Kumar G. Vinod, Varma S. V. K., Kumar R. V. M. S. S. K.

International Journal of Applied Mechanics and Engineering

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2019

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Vol. 24, no. 3

709--724

EN

The stretching sheets with variable thickness may occur in engineering applications more frequently than a flat sheet. Due to its various applications, in the present analysis we considered a three dimensional unsteady MHD nanofluid flow over a stretching sheet with a variable wall thickness in a porous medium. The effects of radiation, viscous dissipation and slip boundary conditions are considered. Buongiorno’s model is incorporated to study the combined effects of thermophoresis and Brownian motion. The dimensionless governing equations are solved by using MATLAB bvp4c package. The impact of various important flow parameters is presented and analysed through graphs and tables. It is interesting to note that all the three boundary layer thicknesses are diminished by slip parameters. Further, the unsteady parameter decreases the hydromagnetic boundary layer thickness.