Unsteady MHD Mixed Convection Flow with Slip of a Nanofluid in the Stagnation Region of an Impulsively Rotating Sphere with Effects of Thermal Radiation and Convective Boundary Conditions

Abstract

Unsteady magnetohydrodynamic mixed convection flow of an electrically conducting nanofluid in a stagnation region of a rotating sphere is studied numerically in the present article. Slip and convective boundary conditions are imposed to surface of the sphere and the thermal radiation effects are taken into account. The nanofluid is simulated using Buongiorno’s nanofluid model and the nanofluid particle fraction on the boundary is considered to be passively rather than actively controlled. Non-similar solutions are applied on the governing equations and the MATLAB function bvp4c is used to solve the resulting system. Effects of the key-parameters such as slip parameter, Biot number, radiation parameter, rotation parameter, Lewis number and Brownian motion parameter on the fluid flow, temperature and nanoparticle volume fraction characteristics are examined. Details of the numerical solution and a comprehensive discussion with the physical meaning for the obtained results are performed. The results indicated that the increase in slip parameter enhances the velocity profiles, while it decreases the temperature distributions. Also, the increase in either slip parameter or Biot number causes an improvement in the rate of heat transfer.