A Comparative Study of Newtonian and Non-Newtonian Nanofluids with Variable Thermal Conductivity Over a 3-D Stretching Surface

Abstract

This study presents a comprehensive numerical and statistical analysis of the flow, heat/mass transfer management of Newtonian and non-Newtonian nanofluid over a bidirectional Darcy-Forchheimer stretching sheet. The external effects of MHD, Joule heating, thermal radiation, heat generation/absorption, Brownian motion, thermal diffusion and chemical reaction are taken into account. It is presumed that the thermal conductivity of fluid varies linearly with temperature. The non-linear coupled P.D.Es are converted into nonlinear coupled O.D.Es using similarity transformation. These equations are solved using MATLAB by implementing four-stage Lobatto IIIa formula and the outcomes of numerous flow parameters are presented graphically. In addition to numerical investigations, a comprehensive statistical analysis is performed using R-software to evaluate the sensitivity of key input parameters towards variable thermal conductivity. The values of local wall friction, local wall heat flux, and wall mass flux for various parameters are tabulated. The study reveals that the heat transmission is significant for dilatant fluids (156.8%) when compared to the pseudoplastic fluids (113.8%). Enriching the values of the Brownian motion parameter suppresses the molecular diffusion while a contrary nature is observed for the thermal diffusion parameter. Further, the mass transfer coefficient shows a very strong negative correlation with variable thermal conductivity parameter for Shear thinning fluids, whereas for Newtonian and Shear thickening fluids it shows a very strong positive correlation.