Nanoparticle‐dependent viscosity, thermal diffusion and diffusion‐thermo effects on mixed convection nanofluid flow with convective boundary

Abstract Assumption of constant viscosity in model design potentially compromises the quantitative accuracy that is required to perfect designs of engineering systems. As such, quantitative improvement of these results is achievable by considering viscosity of fluid that vary with either temperature or concentration or both. The present investigation presents the variation of viscosity as a composite function of temperature and nanoparticle volume fraction. In addition, it investigates the combined effects of solutal and thermal gradients on the heat and mass transfer flow of water carrying nanoparticles over a semi‐infinite plate with a convective boundary. We modeled and analyzed the mixed convection phenomenon with Dufour and Soret influence, viscosity, and nanoparticle volume variations in the boundary layer region of flow formation, concentration, nanoparticles volume fraction, and thermodynamics. Using an appropriate dimensionless transformation, the governing equations were reformulated and solved using the Spectral Local Linearization Method. The findings indicate that nanofluid hydrodynamics and thermodynamics can be enhanced by reducing viscosity, while increasing the Dufour effect improves nanoparticle mass, regular mass, nanoparticle volume fraction, and heat transfer on the boundary. The flow drag force significantly reduces by 28.8%, 16.5%, and 2.6% with the introduction of temperature‐dependent variable viscosity , an increased nanoparticle ratio , and Soret effect , respectively. Although Dufour number enhances the drag force by about 27.0%, , , and generate a corresponding percentage rise of 5.4, 14.9, and 251.4, respectively, to heat transfer coefficient.