Computational analysis of mixed convection in a channel with a cavity heated from different sides ☆ M.M. Rahman a, b, ⁎, Hakan F. Öztop c, e , N.A. Rahim a , R. Saidur a, d , K. Al-Salem e , N. Amin a , M.A.H. Mamun f , A. Ahsan g a Centre of Research UMPEDAC, Level 4, Engineering Tower, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia b Department of Mathematics, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh c Department of Mechanical Engineering, Technology Faculty, Fırat University, Elazig, Turkey d Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia e Department of Mechanical Engineering, College of Engineering, King Saud University, Riyadh, Saudi Arabia f Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh g Department of Civil Engineering, Faculty of Engineering, (and Green Engineering and Sustainable Technology Lab, Institute of Advanced Technology), University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia abstract article info Available online 22 September 2011 Keywords: Channel Cavity Magnetic field Convection heat transfer A computational work is performed in this paper to analyze the heat transfer, temperature distribution and flow field in a channel with a cavity heated from different sides. Flow inlets to the channel are uniform. Constant mag- netic field is applied to the channel as Ha=10, Prandtl number is chosen as Pr=0.7 and Reynolds number is fixed at Re = 100. Finite element method is used to solve governing equations. Three different cases were consid- ered based on heater position in the cavity at the left vertical side (Case 1), bottom side (Case 2) and right vertical side (Case 3). It is found that the highest heat transfer is obtained when the isothermal heater is located at the right vertical wall. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction Simultaneous convection of buoyancy and forced convection is called as combined or mixed convection, which is of great interest in en- gineering applications such as nuclear reactors, lakes and reservoirs, cooling process of electronic devices, solar applications, combustion chambers, food processing and float glass production in industry. These applications are found in Refs. [1–5]. Heater position to the flowing fluid is very important from the effi- ciency of the mixed heating or cooling process. In this context, Manca et al. [6] studied the problem of mixed convection in an open cavity with a heated wall bounded by a horizontally insulated plate. They took into account three heating modes as assisting flow, opposing flow and heating from below by applying constant heat flux. In their configuration, there is no inlet section and it suddenly extends to the cavity. They showed that the maximum temperature values decrease as the Reynolds and Richardson numbers increase. Manca et al. [7] made an experimental work on mixed convection in an open cavity with a heated wall bounded by a horizontal unheated plate. Their flow visualization shows that for Re=1000, there are two nearly distinct fluid motions as a parallel forced flow in the channel and a recir- culation flow inside the cavity. Mixed convection in an obstructed cavity with heated horizontal walls is carried out by Shi and Vafai [8]. They used Brinkman–Forchheimer–extended Darcy model to describe the flow characteristics within a porous medium for different angles of attack with respect to the forced convection. They found that the aspect ratio increases the thickness of the thermal boundary layer increases, resulting in a decrease in the heat transfer rate through the horizontal walls. Effects of different exit locations on mixed convection heat transfer were analyzed in literature [9–11]. Rahman et al. [12] numerically studied magnetohydrodynamic mixed convection in a horizontal channel with an open cavity. They used Galerkin weighted residual method for the numerical simulation and showed a significant effect of the considered parameters on the flow and thermal fields inside the cavity. Ozalp et al. [13] discussed the effects of shape of cavity by making an experiment, and they measured velocities by using PIV. They observed that maximum Reynolds stresses and turbu- lence intensity values were observed in the lid section of the cavity at the centerline position, and rectangular and triangular cavities cause much greater turbulence compared to semi-circular cavity shape. Effects of the aspect ratio on combined convection from an open cavity in a horizontal channel were studied by Leong et al. [14]. On the other hand, it has a striking effect on isotherms and density contours. Heaters may be protruding heaters [15] but it is taken mostly as the flush mounted heater. For example, Oztop [16] is worked a study International Communications in Heat and Mass Transfer 39 (2012) 78–84 ☆ Communicated by W.J. Minkowycz. ⁎ Corresponding author at: Centre of Research UMPEDAC, Level 4, Engineering Tower, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia. E-mail address: m71ramath@gmail.com (M.M. Rahman). 0735-1933/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.icheatmasstransfer.2011.09.006 Contents lists available at SciVerse ScienceDirect International Communications in Heat and Mass Transfer journal homepage: www.elsevier.com/locate/ichmt