Boundary layer heat and mass transfer with Cattaneo-Christov double-diffusion in upper-convected Maxwell nanofluid past a stretching sheet with slip velocity

A systematic study is presented for the boundary layer Cattaneo-Christov double-diffusion model of heat and mass transfer in an upper-convected Maxwell nanofluid over a stretching sheet. The innovative constitutive model, namely Cattaneo-Christov upper-convected material derivative, is first introduced in characterizing the boundary layer slip shear flow, thermal diffusion and nanoparticles concentration diffusion. Viscoelastic relaxation framework system of upper-convected Maxwell nanofluid is constructed uniquely in which heat and mass transfer are both determined by Cattaneo-Christov model uniformly. The effects of Brownian motion & thermophoresis and the dynamic viscosity assumed as the linear function of temperature are taken into account. The highly coupled boundary layer governing equations including momentum, energy & mass conservation equations are transformed to similarity equations via appropriate dimensionless variables. The velocity, temperature & concentration distributions affected by respective relaxation parameters are obtained by homotopy analysis method (HAM) and analyzed thoroughly. Results indicated that this viscoelastic relaxation framework system makes us possible to predict the relaxation times transport characteristics. The internal elastic stress aggregates initially (with big skin friction) and then release (small stress) along with the development of the boundary layer, which is the main reason to generate macroscopic relaxation phenomena. Moreover, the effects of velocity slip on boundary layer transport are also discussed. (C) 2016 Elsevier Masson SAS. All rights reserved.