Cattaneo-Christov dual diffusive non-Newtonian nanoliquid flow featuring nonlinear convection

Abstract

A theoretical study is presented of the transport characteristics in double diffusive tangent hyperbolic (non-Newtonian) nanofluid boundary layer flow from a stretching flat surface. The Cattaneo–Christov (non-Fourier and non-Fickian) double diffusion model is deployed in the formulations for energy and species conservation, to determine more precisely temperature and concentration distributions with thermal and solutual relaxation times. Non–linear mixed convection and heat generation/absorption are included. The nanofluid approach combines Brownian motion and thermophoresis. Suitable transformations are deployed to render the nonlinear partial differential system into a system of dimensionless coupled ordinary nonlinear differential equations. The non-dimensional boundary value problem is then solved with the homotopic analysis method (HAM). The distributions of velocity, temperature and concentration of nanoparticles are depicted and investigated for the effects of multiple emerging parameters. Velocity is reduced (and momentum boundary layer thickness elevated) with increasing power–law index and Weissenberg number whereas velocity is elevated (and momentum boundary layer thickness reduced) with increment in mixed convection variable. Temperature is suppressed (and thermal boundary layer thickness depleted) with increasing thermal relaxation variable, heat sink parameter, Prandtl number whereas temperature is enhanced (and thermal boundary layer thickness boosted) with greater heat source parameter, Brownian motion parameter and thermophoresis parameter. Nanoparticle concentration is depleted (and concentration boundary layer thickness reduced) with greater Schmidt number and Brownian motion parameter whereas the opposite effect is induced with greater thermophoresis parameter and solutal relaxation time. Skin friction is strongly reduced with increasing values of nonlinear thermal and concentration convection variables. The simulations are relevant to nano-polymer coating operations.