Unsteady mixed convection flow of variable viscosity nanofluid in a micro-channel filled with a porous medium

Nanofluids flow and heat transfer in micro-channels have a wide range of attributes in industrial process as well as engineering and biomedical applications. Therefore, the aim of this study is to analyze the hydrodynamic and thermal behaviors of unsteady mixed convection flow of nanofluid in a micro-channel filed with a saturated porous medium. The highly nonlinear governing partial differential equations corresponding to the momentum, energy and concentration profiles were formulated and solved numerically by utilizing the semi-discretization finite difference method. The effects of each governing thermophysical parameters on the micro-channel hydrodynamic and thermal behaviors are discussed with the usage of graphs. The numerical results indicate that the velocity and temperature profiles show an increasing behavior with pressure gradient parameter, variable viscosity parameter, Eckert number, thermal Grashof number, solutal Grashof number and thermophoresis parameter, whereas the concentration profile increases with increasing values of suction/injection Reynolds number, porous medium shape parameter, Forchheimer number, Prandtl number, Schmidt number and thermophoresis parameter. Moreover, the result reveals that the skin friction coefficient, the Nusselt number and the Sherwood number are higher for large values of pressure gradient parameter, thermal Grashof number, Prandtl number and Schmidt number. (author)