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The effects of a chemical reaction and radiative heat flux in a nonlinear mixed thermo-solutal convection flow of a viscoelastic nanoliquid from a stretchable surface are investigated theoretically. Newtonian heating is also considered. The upper-convected Maxwell (UCM) model is deployed to represent the non-Newtonian characteristics. The model also includes the influence of thermal radiation that is simulated via an algebraic flux model. Buongiorno’s two-component nanofluid model is implemented for thermophoretic and Brownian motion effects. Convective thermal and solutal boundary conditions are utilized to provide a more comprehensive evaluation of temperature and concentration distributions. Dimensionless equations are used to create the flow model by utilizing the appropriate parameters. The computed models are presented through a convergent homotopic analysis method (HAM) approach with the help of Mathematica-12 symbolic software. Authentication of HAM solutions with special cases from the literature is presented. The impact of various thermophysical, nanoscale and rheological parameters on transport characteristics is visualized graphically and interpreted in detail. Temperatures are strongly enhanced with Brownian motion and thermophoresis parameters. Velocity is boosted with the increment in the Deborah viscoelastic number and mixed convection parameter, and the hydrodynamic boundary layer thickness is reduced. A stronger generative chemical reaction enhances concentration magnitudes, whereas an increment in the destructive chemical reaction reduces them and also depletes the concentration boundary layer thickness. Temperature and concentration are also strongly modified by the conjugate thermal and solutal parameters. Greater radiative flux also enhances the thermal boundary layer thickness. Increasing the Schmidt number and the Brownian motion parameter diminish the concentration values, whereas they elevate the Sherwood number magnitudes, i.e. enhance the nanoparticle mass transfer rate to the wall.

The primary objective of this investigation is to explore the Cattaneo–Christov flux models impact on Williamson nanofluid over a stretching surface. Buongiorno’s model featuring diffusions (Brownian and thermophoretic) is opted for nonlinear analysis. Buoyancy-driven nonlinear convection flow in stagnation region is modeled. Surface is permeable and transpiration effects are considered. Energy expression captures heat source/sink aspects. The nondimensional differential systems are tackled analytically via homotopy analysis method (HAM). The profiles of dimensionless temperature, concentration and skin friction are examined graphically for the attributes of multiple physical parameters. It is revealed that the heat transfer elevates with the increment of thermophoresis, heat source and Brownian motion parameters while it dwindles with the improvement of thermal relaxation parameter. The mass transfer strengthens with the enlargement of thermophoresis parameter while diminishing with the enhancement of solutal relaxation and Brownian motion parameters. The skin friction is elevated for higher values of material variable against nonlinear mixed convection parameter.

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This research reports the thermo-solutal mixed convective non-Newtonian (tangent-hyperbolic) fluid flow from a stretchable surface under the effect of viscous dissipation. Impermeable surface with stratifications (thermal and solutal) creates the flow. The Buongiorno nanoliquid model capturing Brownian diffusion and thermophoresis is opted for analysis. Energy expression modeling is based on heat source/sink and thermal radiation. Consideration of chemical reaction accounts for species concentration. Via relevant transformations, the flow model of nonlinear governing partial differential conservation equations and free-stream boundary conditions are extracted into coupled nonlinear ordinary differential equations which are solved analytically using homotopy technique. Comparative results ensuring the soundness of the employed technique are included. Analytical results are presented graphically for the influence of pertinent parameters on velocity, temperature, skin-friction coefficient, local Nusselt and Sherwood numbers. The obtained outcomes witness that the concentration of nanoparticles is increased with stronger values of thermophoresis and concentration Biot number while it declines with increasing values of solutal stratification variable, Brownian motion and Schmidt number.