Numerical study of the Thermo-hydrodynamic behavior of a non-Newtonian nanofluid in a backward facing step

Abstract

Abstract In the present work, a numerical simulation of a laminar non-isothermal flow of a non-Newtonian nanofluid in a backward facing step (BFS) is presented. It deals with Cu-water nanofluid, where the mixture shows a shear thinning behavior flowing from the restricted part of the duct with a fully developed velocity and a cold temperature. The lower part of the extended area of the backward facing step is maintained at a hot temperature, while all the other boundaries are considered thermally insulated. Moreover, a uniform magnetic field according to different angle is applicated on the nanofluid flow. The numerical simulation is based on the resolution of the mass, momentum and energy balance equations using Comsol Multiphysics. The aim of the sensitivity study is to highlight the impact of the Reynolds number, the nanoparticles concentration, the Hartmann number and the angle of the magnetic field on the flow and the thermal behaviours, as well as on the Nusselt number. Surprisingly, the results show that an increase in the Hartmann number, corresponding to a more intense magnetic field, resulted in a significant reduction in flow intensity.