Computational magnetohydrodynamics of a Fe3O4-water-based nanofluid flow over a nonlinear stretching surface with velocity and thermal wall slip under variations in the shape factor

Purpose The shape factor of nanoparticles is a parameter of interest in the variation of the thermophysical properties of nanofluids, and it affects their fluid flow and temperature distribution. Hence, this study aims to focus on analysing the influence of the shape factor on the convective heat and mass transfer over a nonlinear stretching sheet under the influence of magnetohydronamics. Design/methodology/approach By using similarity transformations, the governing system of partial differential equations was simplified to a nonlinear ordinary differential equation system, which was solved numerically using an explicit finite difference method (Keller box method). The behaviour of the fluid velocity and thermal profile at the boundary, as a result of slip conditions, is studied through a comprehensive parameter exploration. Findings The behaviour of the fluid velocity and thermal profile at the boundary, as a result of slip conditions, is studied by a very extensive parameter exploration. The major findings reveal that increasing values of magnetic parameters promote Lorentz’s force, which slows down the velocity profile. Increasing the stretching rate parameter causes deformation reducing both the velocity and temperature profile. It is found that the temperature rise for elevated values of a thermophoretic parameter is greater for brick-shaped nanoparticles. It is also observed that the heat transfer (Nusselt number) for augmented values of Eckert number is lower in brick-shaped nanoparticles compared to platelet-shaped nanoparticles. Research limitations/implications The main limitation of this work has been the two-dimensional nature of the modelling, the analysis of a certain range of parameters that may not suit all the reader interests and the assumption of specific functions for the stretched sheet velocity and temperature, as well as the magnetic field. Also, regarding the nanofluid characteristics, it has been considered as single-phase, with Fe3O4 particles only and Newtonian. Originality/value This manuscript analyzes mathematically important aspects of the behaviour of a nanofluid with nanoparticles in magnetohydrodynamics of a non-linearly stretched sheet. This work is a detailed parametric exploration (magnetic parameter, stretching parameter, slip parameters, Brownian motion parameter, thermophoretic parameter, Ecker number, Lewis number and solid volume fraction) of the behaviour of two different nanoparticle shapes (brick and platelet), which sheds light on relevant aspects such as, skin friction, heat transfer and mass transfer. These are valuable results for the scientific community for either perform their numerical analysis upon these results and methodology, or perform experimental prototyping according to the behaviour described in this manuscript.