Yahaya Shagaiya Daniel

Effects of slip and convective conditions on MHD flow of nanofluid over a porous nonlinear stretching/shrinking sheet

Abstract The purpose of this paper is to theoretically investigate the steady two-dimensional electrical magnetohydrodynamic (MHD) nanofluid flow over a stretching/shrinking sheet. The effects of stretching and shrinking parameter, as well as electric and magnetic fields, thermal radiation, viscous and Joule heating in the presence of slip, heat and mass convection boundary conditions at the surface, are imposed and studied. The mathematical model governing the flow has been constructed which are partial differential equations and then rehabilitated for a system of ordinary differential equations involving the momentum, energy and concentration equations via suitable similarity transformations. Though various conjectures have been put forward to explain the concept of boundary layer flow, the current investigation employed implicit finite difference scheme indicates good agreement with those of the previously published investigation in the limiting sense. Numerical results of the dual solutions for the velocity, temperature, and concentration as well as heat transfer are elucidated through graphs and tables. The velocity, thermal and solutal boundary layer thickness in the first solutions is smaller than that of the second solutions, the first solution is more stable compared to the second solution. Temperature and nanoparticle concentration fields are augmented by the heat and mass convective boundary conditions.

Thermal stratification effects on MHD radiative flow of nanofluid over nonlinear stretching sheet with variable thickness

The combined effects of thermal stratification, applied electric and magnetic fields, thermal radiation, viscous dissipation and Joules heating are numerically studied on a boundary layer flow of electrical conducting nanofluid over a nonlinearly stretching sheet with variable thickness. The governing equations which are partial differential equations are converted to a couple of ordinary differential equations with suitable similarity transformation techniques and are solved using implicit finite difference scheme. The electrical conducting nanofluid particle fraction on the boundary is passively rather than actively controlled. The effects of the emerging parameters on the electrical conducting nanofluid velocity, temperature, and nanoparticles concentration volume fraction with skin friction, heat transfer characteristics are examined with the aids of graphs and tabular form. It is observed that the variable thickness enhances the fluid velocity, temperature, and nanoparticle concentration volume fraction. The heat and mass transfer rate at the surface increases with thermal stratification resulting to a reduction in the fluid temperature. Electric field enhances the nanofluid velocity which resolved the sticking effects caused by a magnetic field which suppressed the profiles. Radiative heat transfer and viscous dissipation are sensitive to an increase in the fluid temperature and thicker thermal boundary layer thickness. Comparison with published results is examined and presented.

Hydromagnetic slip flow of nanofluid with thermal stratification and convective heating

Abstract A numerical study of combined effects of thermal stratification and convective heating for the two-dimensional unsteady flow of hydromagnetic natural convection of nanofluid with buoyancy effects against permeable stretching sheet in presence of electric field is presented. Viscous dissipation and Ohmic heating, as well as radiative heat transfer, are taken into account in the heat convection field. The impact of the chemical reaction due to zero flux of nanoparticle concentration is adopted. The model associated with Brownian motion and thermophoretic diffusion is controlled with slip flow as well as the convective boundary conditions with effects of thermal stratification are employed. Suitable similarity transformations are utilised to transform the governing equations into a couple of ordinary differential equations. The transformed equations systems are then solved numerically using Keller box method. The effects of the pertinent parameters on dimensionless nanofluid velocity, temperature and concentration as well as the skin friction, and Nusselt number are examined. The numerical data obtained in the present investigation are validated and are in good agreement with the previously published data. The numerical computations reveal that that electric and magnetic fields exhibit opposite’s flow behaviour due to fluid motion and both enhance the fluid temperature field. The consequence of convective heating intensifies the nanofluid temperature for higher values as thermal stratification reduces the profiles and its associate’s thermal boundary layer thickness.