LAUSR

In this study we investigated unsteady mixed convection flow and heat transfer of radiating and reacting nanofluid with variable transport properties in a microchannel filed with a saturated porous medium by taking into account the convective boundary conditions. The Buongiorno’s nanofluid flow model is used to study the effects of the Brownian motion and the thermophoresis. The governing highly nonlinear partial differential equations corresponding to the momentum, energy and concentration profiles have been formulated and solved numerically by utilizing the semi-discretization finite difference method. The effect of each governing thermophysical parameters on the microchannel hydrodynamic and thermal behaviors is discussed with the usage of graphs. The numerical results indicate that the velocity and temperature profiles show an increasing behavior with the variable viscosity parameter, Eckert number, thermal Grashof number, solutal Grashof number, Prandtl number and chemical reaction parameter, whereas the concentration profile increases with increasing values of variable thermal conductivity parameter, porous medium shape parameter, Forchheimer number, Brownian motion parameter, Schmidt number, Biot number and radiation parameter. Moreover, the result reveals that the skin friction coefficient increases with suction/injection Reynolds number, porous medium shape parameter, thermal Grashof number, Schmidt number and Brownian motion parameter but decreases with Eckert number, thermophoresis parameter, Biot number and radiation parameter. Both the heat transfer and the mass transfer rates at both sides of the microchannel walls are higher for large values of suction/injection Reynolds number, porous medium shape parameter and variable viscosity parameter, while both are lower for large values of Eckert number, variable thermal conductivity parameter and radiation parameter. Besides, Grashof number, Schmidt number and Biot number indicate an increasing effect on both the heat transfer and mass transfer rates at the cold wall of the microchannel. The numerical simulation also reveals that Brownian motion parameter and thermophoresis parameter show an opposite effect on both heat transfer and mass transfer rates at both sides of the microchannel walls.