Entropy analysis for magnetohydrodynamic flow and heat transfer of a Jeffrey nanofluid over a stretching sheet

Entropy generation for steady laminar two-dimensional forced convection magnetohydrodynamic (MHD) boundary layer flow, heat transfer and mass transfer of an incompressible non-Newtonian nanofluid over a linearly stretching, impermeable and isothermal sheet with viscous dissipation is numerically studied. The nanofluid model is considered by using the Brownian motion and thermophoresis effects. The Jeffrey model is used to denote the non-Newtonian fluid. The boundary layer continuity, momentum, energy, and concentration equations are transformed by using appropriate similarity transformations to three nonlinear coupled ordinary differential equations (ODEs). Then, the ODEs are solved by applying an implicit Keller's box numerical algorithm. The influence of various controlling parameters including ratio of relaxation to retardation times, Deborah number, Eckert number, Brownian motion parameter, thermophoresis parameter, and Lewis number on flow, heat transfer, mass transfer, and entropy generation characteristics is examined and discussed. Graphical presentation of the numerical examination is performed to illustrate the influence of various parameters on velocity, temperature, nanoparticles volume fraction, and entropy generation number profiles. The results reveal that the entropy generation number strongly varies by variations in Reynolds number, Prandtl number, Lewis number, and thermophoresis parameter. A comparative study of our numerical results with the results from previous works is also performed which shows excellent agreement. (C) 2014 Elsevier Ltd. All rights reserved.