Abstract
Presently we have studied the nonlinear magnetohydrodynamic convective boundary-layer flow of water- based nano-ferrofluid adjacent to a non-isothermal stretching sheet. Three different ferrofluid suspensions are considered, namely water containing magnetite (Fe3O4), (Mn - Zn)and cobalt ferrite (CoFe2O4) ferriteferro-particles. Magnetic field is sufficiently strong to induce induction effects. Applying similarity transformations, the boundary region equations for mass, momentum, magnetic induction and energy are reduced to coupled, multi-degree, nonlinear differential equations. The non-dimensional boundary value problem is then solved computationally under specified wall and free stream conditions, with Maple quadrature and shooting techniques. Non-isothermal as well as constant heat flux cases are examined. The key parameters emerging in the model are the reciprocal of magnetic Prandtl number, Prandtl number, the reciprocal of magnetic body force parameter, heat source/sink parameter, nano-particle volume fraction and power-law index. The influence of these parameters on flow fields like velocity, temperature, and gradient of magnetic stream function for different ferro-particle cases, is presented graphically. Detailed elucidation of the results is also included. Validation is conducted with a finite element method (FEM). Significantly greater temperatures are observed for magnetite ferro-particles as compared with cobalt or Manganese-Zinc ferroparticles. Stream function (Magnetic) is found to be suppressed with increasing power-law index. With increasing magnetic force number there is a substantial elevation in induced magnetic field. Increasing reciprocal of magnetic Prandtl number i.e. decreasing magnetic Prandtl number leads to a depression in velocity i.e. flow deceleration, for the Fe3O4 - H2O magnetite ferrofluid. The study proposed here is of concern to the processing of nano-ferro-materials.