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ARTICLE

Numerical Investigation of the Influence of a Magnetic Field on the Laminar Flow of a Yield-Stress Nanofluid over a Backward Facing Step

Karim Amrani^1,*, Eugenia Rossi di Schio^2,*, Mohamed Bouzit³, Abderrahim Mokhefi^1,4, Abdelkader Aris¹, Cherif Belhout³, Paolo Valdiserri²

1 Mechanical Manufacturing Technology Research Laboratory (LaRTFM), National Polytechnic School of Oran Maurice Audin, El mnaouar, Bp 1523, Es-senia, Oran, 31000, Algeria
2 Department of Industrial Engineering DIN, Alma Mater Studiorum-University of Bologna, Viale Risorgimento 2, Bologna, 40136, Italy
3 Laboratory of Maritime Sciences and Engineering, LSIM Faculty of Mechanical Engineering, University of Science and Technology of Oran, Mohamed Boudiaf, El Mnaouer, Oran, 31000, Algeria
4 Mechanics, Modeling and Experimentation Laboratory L2ME, Faculty of Sciences and Technology, Bechar University, Bechar, 08000, Algeria

* Corresponding Authors: Karim Amrani. Email: ; Eugenia Rossi di Schio. Email:

(This article belongs to the Special Issue: Heat Transfer Enhancement for Energy Applications)

Frontiers in Heat and Mass Transfer 2025, 23(1), 185-206. https://doi.org/10.32604/fhmt.2025.059833

Received 17 October 2024; Accepted 25 December 2024; Issue published 26 February 2025

Abstract

The present study focuses on the flow of a yield-stress (Bingham) nanofluid, consisting of suspended Fe₃O₄ nanoparticles, subjected to a magnetic field in a backward-facing step duct (BFS) configuration. The duct is equipped with a cylindrical obstacle, where the lower wall is kept at a constant temperature. The yield-stress nanofluid enters this duct at a cold temperature with fully developed velocity. The aim of the present investigation is to explore the influence of flow velocity (Re = 10 to 200), nanoparticle concentration ( = 0 to 0.1), magnetic field intensity (Ha = 0 to 100), and its inclination angle (γ = 0 to 90) and nanofluid yield stress (Bn = 0 to 20) on the thermal and hydrodynamic efficiency inside the backward-facing step. The numerical results have been obtained by resolving the momentum and energy balance equations using the Galerkin finite element method. The obtained results have indicated that an increase in Reynolds number and nanoparticle volume fraction enhances heat transfer. In contrast, a significant reduction is observed with an increase in Hartmann and Bingham numbers, resulting in quasi-immobilization of the fluid under the magnetic influence and radical solidification of this type of fluid, accompanied by the suppression of the vortex zone downstream of the cylindrical obstacle. This study sheds light on the complexity of this magnetically influenced fluid, with potential implications in various engineering and materials science fields.

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