Abstract
The unsteady two-dimensional laminar g-Jitter mixed convective boundary layer flow of Cu-water and Al2O3-water nanofluids past a permeable stretching sheet in a Darcian porous is studied by using an implicit finite difference numerical method with quasi-linearization technique. It is assumed that the plate is subjected to velocity and thermal slip boundary conditions. We have considered temperature dependent viscosity. The governing boundary layer equations are converted into non-similar equations using suitable transformations, before being solved numerically. The transport equations have been shown to be controlled by a number of parameters including viscosity parameter, Darcy number, nanoparticle volume fraction, Prandtl number, velocity slip, thermal slip, suction/injection and mixed convection parameters. The dimensionless velocity and temperature profiles as well as friction factor and heat transfer rates are presented graphically and discussed. It is found that the velocity reduces with velocity slip parameter for both nanofluids for fluid with both constant and variable properties. It is further found that the skin friction decreases with both Darcy number and momentum slip parameter while it increases with viscosity variation parameter. The surface temperature increases as the dimensionless time increases for both nanofluids. Nusselt numbers increase with mixed convection parameter and Darcy numbers and decreases with the momentum slip. Excellent agreement is found between the numerical results of the present paper with published results.
Highlights
The presence of temperature gradient and gravitational field yields convective flows in clear as well as porous media
We investigate the effects of linear hydrodynamic slip, thermal slip and temperature dependent viscosity on g-Jitter mixed convective boundary layer flow of nanofluid past a permeable stretching sheet in a Darcian porous media
The effects of viscosity variation and velocity slip parameters on the dimensionless velocity are compared for Cuwater and Al2O3-water nanofluids in Figs. 2(a) and 2(b)
Summary
The presence of temperature gradient and gravitational field yields convective flows in clear as well as porous media. Pal and Mondal [45] investigated the effect of variable viscosity on mixed convection flow and heat transfer along a stretching sheet a in a non-Darcy porous medium. In order to get the real picture of the flow, heat and mass transfer characteristics in the nanofluids, it is required to take into the effect of the temperature-dependent viscosity of the base fluid. We investigate the effects of linear hydrodynamic slip, thermal slip and temperature dependent viscosity on g-Jitter mixed convective boundary layer flow of nanofluid past a permeable stretching sheet in a Darcian porous media.
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