Semnan University Press Journal of Heat and Mass Transfer Research 2345-508X 13 3 2026 09 01 Investigation of a Flexible V-Fin for Heat Transfer Enhancement in a Backward-Facing Step بررسی یک پره V شکل انعطاف‌پذیر برای افزایش انتقال حرارت در یک پله رو به عقب 295 313 10290 10.22075/jhmtr.2025.38745.1809 EN Ikram Djellid Institute of Industrial Maintenance and Safety, University of Oran 2 Mohamed Ben Ahmed, Laboratory of Production Engineering and Industrial Maintenance (LGPMI), B.P. 170 El M’naouer Oran 31000, Algeria Noureddine Bouhamri Institute of Industrial Maintenance and Safety, University of Oran 2 Mohamed Ben Ahmed, Laboratory of Production Engineering and Industrial Maintenance (LGPMI), B.P. 170 El M’naouer Oran 31000, Algeria Mohamed Bouhafs Institute of Industrial Maintenance and Safety, University of Oran 2 Mohamed Ben Ahmed, Laboratory of Production Engineering and Industrial Maintenance (LGPMI), B.P. 170 El M’naouer Oran 31000, Algeria Mohamed Bouzit Faculty of Mechanical Engineering, University of Science and Technology of Oran Mohamed Boudiaf, El M’naouer, Laboratory of Maritime Sciences and Engineering (LSIM), B.P.1505, 31000, Oran, Algeria 0000-0002-1417-7291 Ikram Boualem Institute of Industrial Maintenance and Safety, University of Oran 2 Mohamed Ben Ahmed, Laboratory of Production Engineering and Industrial Maintenance (LGPMI), B.P. 170 El M’naouer Oran 31000, Algeria Journal Article 2025 08 20 A numerical study was conducted to enhance heat transfer in a backward-facing step configuration via forced convection. Using the finite element method, simulations were performed for Reynolds numbers from 50 to 200. A flexible V-fin was introduced to direct the coolant (air) flow toward the heated wall. The fin's vertical position (<em>y</em> = 0, <em>H</em>/10, <em>H</em>/5) and elasticity, governed by the Cauchy number (<em>Ca</em> = 10⁻⁴, 10⁻⁵, 10⁻⁶, 10⁻⁷), were key variables. The optimal configuration (<em>y</em> = <em>H</em>/5, <em>Ca</em> = 10⁻⁷, <em>Re</em> = 200) yielded a 30.75% increase in the average Nusselt number over the baseline without a fin. The results confirm that the fin consistently improves thermal performance, whether rigid or flexible. This study employs finite element simulations to analyze forced convection heat transfer in a backward-facing step channel. The research investigates the effect of a flexible V-fin. compared to the case without a fin. Crucially, the fin's presence improved heat transfer performance regardless of its rigidity. https://jhmtr.semnan.ac.ir/article_10290_3e0718dfb46b3bb9851d2030102871c5.pdf