MHD convective heat transfer of Ag-MgO/water hybrid nanoﬂuid in a channel with active heaters and coolers Yuan Ma a,b , Rasul Mohebbi c,⇑ , M.M. Rashidi a,b , Zhigang Yang a,b,d a Shanghai Automotive Wind Tunnel Center, Tongji University, No. 4800, Cao’an Road, Shanghai 201804, China b Shanghai Key Lab of Vehicle Aerodynamics and Vehicle Thermal Management Systems, No. 4800, Cao’an Road, Shanghai 201804, China c School of Engineering, Damghan University, Damghan P.O. Box: 3671641167, Iran d Beijing Aeronautical Science & Technology Research Institute, Beijing 102211, China article info Article history: Received 30 November 2018 Received in revised form 20 March 2019 Accepted 29 March 2019 Keywords: MHD Hybrid nanoﬂuid Forced convection LBM Corrugated channel abstract A two-dimensional (2D) numerical simulation is presented to study the effect of magnetic ﬁeld on Ag- MgO nanoﬂuid forced convection and heat transfer in a channel with active heaters and coolers. A Fortran code according to Lattice Boltzmann method (LBM) is developed for this purpose. The effects of thermal arrangement (Case1, 2 and 3), block side length (0.3  h  0.5), Reynolds number (50  Re  100), Hartmann number (0  Ha  60) and volume fraction of nanoparticles (0  /  0.02) on ﬂow pattern and heat transfer characteristics are analyzed systematically. The obtained results showed that the highest value of local Nusselt number occurs at the junction of the heater and the cooler due to the high temperature gradient, followed by the sharp corner of heaters and coolers. Moreover, the heat transfer at the heater sharp corner is higher than that of the cooler sharp corner. The average Nusselt numbers indicated that the rate of heat transfer increases with increasing / or decreasing Ha. Finally, the heat transfer rate in Case 1 is more than Case 3 and Case 2. Ó 2019 Elsevier Ltd. All rights reserved. 1. Introduction Fluid ﬂow and heat transfer in a channel has been a popular area of researchers due to its widely application such as heat exchangers and electronic devices [1–3]. Corrugated or extended surfaces is a highly effective conﬁgurations to improve the ﬂuid ﬂow pattern and enhance the heat transfer in heat exchangers. Khoshvaght-Aliabadi [4] numerically studied ﬂow and heat trans- fer characteristics of the sinusoidal-corrugated channels. The parameters including height of channel and length, length of wave and amplitude, phase shift Reynolds number and nanoparticle vol- ume fraction were analyzed. Their results showed that the effect of wave amplitude on Nusselt number was most signiﬁcant than the other parameters. Rashidi et al. [5] investigated the heat transfer and ﬂow ﬁeld in a wavy channel. Mirzaei et al. [6] used the Large Eddy Simulation (LES) to study the ﬂow and heat transfer in a half-corrugated channel. The wave amplitude in their work varies from 0 to 0.15. They found that the occupied area of the vortices depended apparently on the wave amplitude. Ahmed et al. [7] numerically and experimentally investigated heat transfer in different corrugated channels. Three different kinds of channels (trapezoidal, sinusoidal and straight) were con- structed and studied. They found that the heat transfer rate of the trapezoidal-corrugated channel is better than the other two kinds channels. Jafari et al. [8] numerically studied ﬂow and heat transfer in a corrugated channel with pulsating velocity proﬁle. Wang et al. [9] investigated the characteristics of ﬂow and heat transfer in a corrugated channel. They found that the wavy proﬁles affected the pressure drop and heat transfer signiﬁcantly. In order to enhance the heat transfer rate of exchanger, nan- otechnology has received great attention. Nanoﬂuid ﬂow and heat transfer is a topic of considerable contemporary interest both in sciences and engineering [10–12]. Al 2 O 3 /water nanoﬂuid was used by Motlagh and Soltanipour [13] to enhance the heat transfer rate of an inclined cavity. They found that increasing volume fraction of nanoparticles leaded to the increase of average Nusselt number. Khan et al. [14] numerically studied Cu/water nanoﬂuid ﬂow and heat transfer and the effect of the nanoparticle shapes (cylinder, platelet and brick) on the heat transfer rate was considered. Their results showed that the value of ﬂuid temperature obtained the maximum for the platelet-shaped particles. Ali et al. [15] considered Brownian motion to analysis the CuO/ water nanoﬂuid convection in a grooved enclosure. Their results indicated that the thermal boundary conditions signiﬁcantly affect the ﬂow and thermal characteristics. Fe 3 O 4 /water nanoﬂuid was https://doi.org/10.1016/j.ijheatmasstransfer.2019.03.169 0017-9310/Ó 2019 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: rasul_mohebbi@du.ac.ir (R. Mohebbi). International Journal of Heat and Mass Transfer 137 (2019) 714–726 Contents lists available at ScienceDirect International Journal of Heat and Mass Transfer journal homepage: www.elsevier.com/locate/ijhmt