Energy Equipment and Systems

Energy Equipment and Systems

Synergistic flow control via concave vortex generators and magnetic fields: Impacts on flow structure, thermal performance, and irreversibilities

Document Type : Research Paper

Authors
Ali Jalayeri 1
Sahar Soleymani 2
Hadi Barjini Khabbaz 3
1 Department of Mechanical Engineering, Urmia University of Technology, Urmia, Iran
2 Department of Industrial Engineering, Padua University, Padova, Italy
3 Department of Mechanical Engineering, Eqbal Lahoori Institute of Higher Education, Mashhad, Iran
10.22059/ees.2025.2059591.1514
Abstract
This work presents a numerical investigation of ferrofluid flow in a heat exchanger using computational fluid dynamics (CFD) based on the finite volume method (FVM) in ANSYS Fluent. Two flow control techniques are examined: the vortex generator (VG) and the magnetic field (MF) as the Passive and Active flow control methods, respectively. The analysis considers the effects of VG, Reynolds number (Re), angle of attack (α), and the dimensionless magnetic number (Mn), which represents MF intensity. Results indicate that employing the vortex generator (VG) as the sole enhancement method increases heat transfer by 39%, while the MF applied independently achieves a 65% increase. When the two methods are combined, however, they act synergistically, delivering an enhancement of up to 184%. Moreover, at constant Mn, raising the Re reduces the heat transfer rate, and the maximum enhancement of 215% observed at Re = 500 and Mn = 1010. Changing the α alters the thermal behaviour of the vortex structures through enhancing fluid mixing and reducing thermal boundary layers, with optimal heat transfer achieved at 45° and Mn = 7.5×10⁹. Entropy generation analysis confirms that through the dominance of heat transfer over the friction factor, irreversibility is minimized, with reductions of up to 26%. Overall, the study demonstrates that integrating active and passive flow control methods supported by validated CFD simulations can simultaneously boost heat transfer and reduce entropy, offering an effective strategy for designing compact, high-performance heat exchangers.
Keywords
Flow Control
Vortex Generator
Convective Heat Transfer
Magnetic Field
Entropy

Subjects

[1] Joshi SN, Gujarathi YS. A review on active and passive flow control techniques. International Journal on Recent Technologies in Mechanical and Electrical Engineering. 2016;3(4):1-6.https://doi.org/10.1007/s10973-021-11168-5
[2] Sheikholeslami M, Ganji DD. Ferrohydrodynamic and magnetohydrodynamic effects on ferrofluid flow and convective heat transfer. Energy. 2014;75:400-10.https://doi.org/10.1016/j.energy.2014.07.089
[3] Motlagh SY, Soltanipour H. Natural convection of Al2O3-water nanofluid in an inclined cavity using Buongiorno's two-phase model. International Journal of Thermal Sciences. 2017;111:310-20.https://doi.org/10.1016/j.ijthermalsci.2016.08.022
[4] Awais M, Bhuiyan AA. Heat transfer enhancement using different types of vortex generators (VGs): A review on experimental and numerical activities. Thermal Science and Engineering Progress. 2018;5:524-45.https://doi.org/10.1016/j.tsep.2018.02.007
[5] Ebrahimi A, Rikhtegar F, Sabaghan A, Roohi E. Heat transfer and entropy generation in a microchannel with longitudinal vortex generators using nanofluids. Energy. 2016;101:190-201.https://doi.org/10.1016/j.energy.2016.01.102
[6] Mali AK, Jana T, Kaushik M, Choubey G. A survey on control techniques to augment compressible jet mixing. Flow, Turbulence and Combustion. 2025;114(1).https://doi.org/10.1007/s10494-024-00588-6
[7] Karthikeyan K, Harish R. Enhanced aerodynamic performance of NACA4412 airfoil through integrated plasma actuator and Gurney flap flow control. Results in Engineering. 2025;25.https://doi.org/10.1016/j.rineng.2025.103977
[8] Nabhani A, Tousi NM, Coma M, Bugeda G, Bergadà JM. Large-scale horizontal axis wind turbine aerodynamic efficiency optimization using active flow control and synthetic jets. Energy. 2025.https://doi.org/10.1016/j.energy.2025.134940
[9] Sun Y, Qian Y, Wang T, Wang L, Zhu C, Gao Y. Quantitative impact of combining blowing and suction flow control on a floating offshore wind turbine aerodynamic performance under the surge motion. Renewable Energy. 2025;238.https://doi.org/10.1016/j.renene.2024.121945
[10] Lv L, Chen Y, Jiang Y, Wang G, Lu J. Study on effects of magnetic fields of different inhomogeneous on the formation mechanism of microdroplets. Microfluidics and Nanofluidics. 2025;29(1).https://doi.org/10.1007/s10404-024-02780-6
[11] Salehin MN, Saimoon NZ, Ahmed MM, Sarker MRI, Masud MH. Passive flow control devices for road vehicles: A comprehensive review. Engineering Science and Technology, an International Journal. 2025;62.https://doi.org/10.1016/j.jestch.2025.101953
[12] Jia G, Chen C, Wang L, Wang P, Huang B, Wu R. Unsteady hydrodynamic characteristics control of turbine blades by the vortex generators. Ocean Engineering. 2025;324.https://doi.org/10.1016/j.oceaneng.2025.120785
[13] Daugbjerg TS, Crouzier L, Delvallée A, Ogheard F, Pecnik C, Romieu K, et al. Measurement of wettability and surface roughness for metrology and quality control in microfluidics. International Journal of Metrology and Quality Engineering. 2025;16.https://doi.org/10.1051/ijmqe/2024021
[14]  Cao Z, Luo L, Yang X, Yan H, Du W. Effects of turning vane on flow control and heat transfer in ribbed two-pass channel with varied rib patterns. International Journal of Thermal Sciences. 2025;207:
https://doi.org/10.1016/j.ijthermalsci.2024.109342
[15] Jamshed S, Tiwari N. Passive control techniques for heat exchangers: Permeability-driven modulation of vortex shedding and heat transfer enhancement. International Communications in Heat and Mass Transfer. 2025;162.https://doi.org/10.1016/j.icheatmasstransfer.2025.108619
[16] Pillai N, Vural E, Flatau A, editors. Active Flow Control Around a Circular Cylinder Using Helmholtz-Type Pulse Combustion. AIAA SCITECH 2025 Forum; 2025.
[17] Huang S, Li Z-W, Peng W-J, Lin J-R, Huang Z-D, Zeng G-Z. Effect of jet flow control in front of the leading bogie on the aerodynamic drag and underbody slipstream of high-speed trains. Engineering Applications of Computational Fluid Mechanics. 2025;19(1).https://doi.org/10.1080/19942060.2024.2447391
[18] Kumar H, Vander Schaaf JC, Islam SAU, Fidkowski K, Bernstein D, editors. Aerodynamic Flow Control Using Active Bleed Actuation with Variable Channel Width. AIAA SCITECH 2025 Forum; 2025.
[19] Dehghan Afifi M, Jalili B, Mirzaei A, Jalili P, Ganji D. The effects of thermal radiation, thermal conductivity, and variable viscosity on ferrofluid in porous medium under magnetic field. World Journal of Engineering. 2025;22(1).https://doi.org/10.1108/WJE-09-2023-0402
[20] Negi AS, Kumar B, Kumar A, Rawat SK, Yaseen M. Investigation of heat flux and heat source/sink effect on heat transfer ferrofluid (CoFe2O4-H2O) flow in an induced magnetic field with porous medium within the horizontal channel. International Journal of Ambient Energy. 2025;46(1).https://doi.org/10.1080/01430750.2024.2447939
[21] Magdy M, Abbas W, Mekheimer KS, Emam M. Ferro-Fluid Flow and Heat Transfer over Unsteady Stretching Sheet in the Presence of a Nonuniform Magnetic Field. Journal of Nonlinear Mathematical Physics. 2025;32(1).https://doi.org/10.1007/s44198-024-00250-9
[22]  Wang C, Sui J, Wang X, Zhang X, Liu P, Gong B. Vortex flow properties and enhanced heat transfer analysis of ferrofluid in a curved pipe under the coupling of magnetic field force and centrifugal force. Journal of Mechanical Science and Technology. 2025.https://doi.org/10.1007/s12206-024-1237-z
[23] He M, Zhuang Y, Xu W, Feng J-C. Experimental study on thermal performance regulation of composited phase change system using non-uniform magnetic field generated by a Helmholtz coil. Applied Thermal Engineering. 2025.https://doi.org/10.1016/j.applthermaleng.2025.126081
[24] Ramezani A, Khorasani AF, Ayoobi A. Experimental study on transient pool boiling heat transfer of deionized water under an alternating magnetic field. International Communications in Heat and Mass Transfer. 2025;161.https://doi.org/10.1016/j.icheatmasstransfer.2024.108450
[25] Mansouri SM, Bijarchi MA, Hannani LSKK. The effect of rotating magnetic turbulators on the convective heat transfer and pressure drop through a circular tube: Experimental investigation. International Journal of Thermofluids. 2025;26.https://doi.org/10.1016/j.ijft.2025.101108
[26] Benam BP, Mohammadilooey M, Sadaghiani AK, Çakır E, Acar HY, Park HS, et al. On saturated flow boiling heat transfer of deionized water/ferrofluid on structured surfaces with or without external magnetic field. International Journal of Heat and Mass Transfer. 2025;236.https://doi.org/10.1016/j.ijheatmasstransfer.2024.126323
[27] Liao C-C, Li W-K, Lin H-E. Heat Transfer Enhancement in Microchannel Systems Through Geometric Modification of Vortex Generators and Nanofluid Integration: A Numerical Study. Results in Engineering. 2025.https://doi.org/10.1016/j.rineng.2025.104138
[28] Liang X, Min M, Bian K, Cheng J. Study on the enhanced heat transfer and exergy performance of the finned tube heat exchanger with vortex generator. International Journal of Thermal Sciences. 2025;210.https://doi.org/10.1016/j.ijthermalsci.2024.109639
[29] Ifraj NF, Akter F, Fahad MK, Ahmed DH. Thermal-hydraulic performance enhancement with minimum entropy generation of a heat exchanger using fidget spinner vortex generators. International Communications in Heat and Mass Transfer. 2025;162.https://doi.org/10.1016/j.icheatmasstransfer.2025.108610
[30] Perng S-W, Wu HW, Guo Y-L, Liu T-H. Enhancement of thermo-hydraulic transport within a round tube using a twisted-staggered concave/convex dimples tape. International Journal of Numerical Methods for Heat & Fluid Flow. 2025.https://doi.org/10.1108/HFF-08-2024-0614
[31] Boonloi A, Jedsadaratanachai W. Turbulent forced convection in a square duct heat exchanger (SDHX) equipped with combined vortex turbulators (CVT): A numerical investigation. International Communications in Heat and Mass Transfer. 2025;161.https://doi.org/10.1016/j.icheatmasstransfer.2024.108421
[32] Jalayeri A, Soltanipour H, Rezazadeh S. Simultaneous Effects of a Vortex Generator and Magnetic Field on Ferrofluid Convective Heat Transfer in a 3D Channel: First and Second Law Analyses. AUT Journal of Mechanical Engineering. 2024;8(2).https://doi.org/10.22060/ajme.2024.22788.6075
[33] Rahimi R, Jalayeri A, Soltanipour H, Tahmoresnezhad J. Performance prediction of ferrofluid-actuated double tube heat exchanger using deep neural network based on magnetic field parameters. Applied Thermal Engineering. 2025:128228.https://doi.org/10.1016/j.applthermaleng.2025.128228
[34] Soltanipour H. Numerical analysis of two-phase ferrofluid forced convection in an annulus subjected to magnetic sources. Applied Thermal Engineering. 2021;196.https://doi.org/10.1016/j.applthermaleng.2021.117278
[35] Jalayeri A, Rahimi R. A Comparative Study on Heat Transfer and Entropy Generation of Ferrofluid Flowing Through a Double‐Tube Heat Exchanger Subjected to Various Magnetic Fields. International Journal for Numerical Methods in Fluids. 2025.https://doi.org/10.1002/fld.70013
[36] Gavili A, Zabihi F, Isfahani TD, Sabbaghzadeh J. The thermal conductivity of water base ferrofluids under magnetic field. Experimental Thermal and Fluid Science. 2012;41.https://doi.org/10.1016/j.expthermflusci.2012.03.016
[37] Bejan A. Second-law analysis in heat transfer and thermal design.  Advances in heat transfer. 15: Elsevier; 1982. p. 1-58.
[38] Asfer M, Mehta B, Kumar A, Khandekar S, Panigrahi PK. Effect of magnetic field on laminar convective heat transfer characteristics of ferrofluid flowing through a circular stainless steel tube. International Journal of Heat and Fluid Flow. 2016;59.https://doi.org/10.1016/j.ijheatfluidflow.2016.01.009
[39] Aminfar H, Mohammadpourfard M, Zonouzi SA. Numerical study of the ferrofluid flow and heat transfer through a rectangular duct in the presence of a non-uniform transverse magnetic field. Journal of Magnetism and Magnetic materials. 2013;327.https://doi.org/10.1016/j.jmmm.2012.09.011
[40] Hekmat MH, Ziarati KK. Effects of nanoparticles volume fraction and magnetic field gradient on the mixed convection of a ferrofluid in the annulus between vertical concentric cylinders. Applied Thermal Engineering. 2019;152.https://doi.org/10.1016/j.applthermaleng.2019.02.124
[41] Zhou G, Ye Q. Experimental investigations of thermal and flow characteristics of curved trapezoidal winglet type vortex generators. Applied Thermal Engineering. 2012;37:241-8.https://doi.org/10.1016/j.applthermaleng.2011.11.024
[42] Abdollahi A, Shams M. Optimization of shape and angle of attack of winglet vortex generator in a rectangular channel for heat transfer enhancement. Applied Thermal Engineering. 2015;81.https://doi.org/10.1016/j.applthermaleng.2015.01.044
[43] Loukopoulos V, Tzirtzilakis E. Biomagnetic channel flow in spatially varying magnetic field. International journal of engineering science. 2004;42(5-6).https://doi.org/10.1016/j.ijengsci.2003.07.007