Contents lists available at ScienceDirect International Communications in Heat and Mass Transfer journal homepage: www.elsevier.com/locate/ichmt Mixed convection of MHD flow in nanofluid filled and partially heated wavy walled lid-driven enclosure Hakan F. Öztop a , Ahmad Sakhrieh b,c , Eiyad Abu-Nada d,⁎ , Khaled Al-Salem e a Department of Mechanical Engineering, Technology Faculty, Firat University, Elazig, Turkey b Department of Mechanical and Industrial Engineering, American University of Ras Al Khaimah, 10021, United Arab Emirates c Mechanical Engineering Department, The University of Jordan, Amman 11942, Jordan d Department of Mechanical Engineering, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, United Arab Emirates e Department of Mechanical Engineering, College of Engineering, King Saud University, Riyadh, Saudi Arabia ARTICLE INFO Keywords: Wavy walled cavity Lid-driven flow Nanofluids Magnetic field Partial heating ABSTRACT A computational work has been done to investigate the effects of mixed convection of MHD flow in nanofluid filled and partially heated wavy walled lid-driven enclosure. Finite difference method is used to solve governing equations of mixed convection for different parameters as Hartmann number, Richardson number, nanoparticle volume rate in partially heated and wavy walled enclosure. It is found that the rate of heat transfer decreases with increasing the Hartmann number. The rate of heat transfer can be enhanced or reduced by increasing the volume fraction of nanoparticles based on Hartmann and Richardson numbers. 1. Introduction Mixed convection heat transfer and fluid flow in complex shaped geometry are important in engineering due to its wide applications, such as cooling of electronical devices, heat exchangers, solar collec- tors, cooling or heating of buildings. Besides, partial heating of confined spaces attracted many researchers recently. Partial heater was applied in some papers in open literature as seen in review of Oztop et al. [1]. There are many example on partial cooling or heating applications as Guimaraes and Menon [2]. Pioneer of computational studies of natural convection in a nanofluid filled enclosures is Khanafer et al. [3]. Oztop and Abu-Nada [4] conducted a computational solution on natural convection in enclosures with Cu-water nanofluid. They found that heat transfer increases with increasing of length of partial heater and na- noparticle volume fraction. Also, effects of combined convection (nat- ural + forced convection) are studied in nanofluid filled systems. In this context, Mehrez et al. [5] focused on entropy generation analysis in the assisting flow of Cu-water nanofluid in an inclined open cavity and they observed that the main important parameter is the inclination angle. Hussain et al. [6] investigated the effects of magnetic field on entropy generation due to mixed convection of water-alumina nano- fluid flow in a double lid driven cavity with discrete heating. In some problems in engineering, the geometry can be curvilinear. Sheremet et al. [7] solved a problem computationally to make analysis of MHD free convection in a wavy open porous tall cavity filled with nanofluids. The cavity has a corner heater. They obtained that heat transfer enhancement with Rayleigh number (Ra) and heat transfer reduction with Hartmann (Ha) number, while magnetic field inclina- tion angle leads to non-monotonic changes of the heat transfer. Heated wavy walled cavity was applied to a melting problem by Kousksou et al. [8]. In their case, the bottom wavy wall is heated isothermally and the problem solved via finite volume method. Waviness of the wall plays important role on the temperature distribution and flow field and they observed that the rate of the melting increases with the elevation in the magnitude of the amplitude value of the wavy surface. As an original work on insulated wavy walled cavity with natural convection of Al 2 O 3 /water nanofluids is studied by Abu-Nada and Oztop [9]. Influ- ence of a magnetic field on the natural convection and entropy gen- eration was studied by Cho [10] for Cu–water nanofluid in a closed space with complex-wavy surfaces. Their obtained results showed that the mean Nusselt number decreases and entropy generation increases with an increasing wave amplitude. Abu-Nada and Chamkha [11] solved a problem of mixed convection in a water-CuO filled lid-driven cavity with wholly heated wavy wall. They observed that heat transfer http://dx.doi.org/10.1016/j.icheatmasstransfer.2017.05.011 ⁎ Corresponding author. E-mail addresses: ahmad.sakhrieh@aurak.ac.ae (A. Sakhrieh), eiyad.abu-nada@kustar.ac.ae (E. Abu-Nada). International Communications in Heat and Mass Transfer 86 (2017) 42–51 0735-1933/ © 2017 Elsevier Ltd. All rights reserved. MARK