Numerical investigations of flow and heat transfer enhancement in a corrugated channel using nanofluid ☆ M.A. Ahmed, N.H. Shuaib ⁎, M.Z. Yusoff, A.H. Al-Falahi Department of Mechanical Engineering, College of Engineering, Universiti Tenaga Nasional, Jalan IKRAM-UNITEN, 43009 Kajang, Selangor, Malaysia abstract article info Available online 29 August 2011 Keywords: Nanofluid Corrugated channel Laminar heat transfer Finite difference method In this paper, heat transfer and pressure drop characteristics of copper–water nanofluid flow through isother- mally heated corrugated channel are numerically studied. A numerical simulation is carried out by solving the governing continuity, momentum and energy equations for laminar flow in curvilinear coordinates using the Finite Difference (FD) approach. The investigation covers Reynolds number and nanoparticle vol- ume fraction in the ranges of 100–1000 and 0–0.05 respectively. The effects of using the nanofluid on the heat transfer and pressure drop inside the channel are investigated. It is found that the heat transfer enhance- ment increases with increase in the volume fraction of the nanoparticle and Reynolds number, while there is slight increase in pressure drop. Comparisons of the present results with those available in literature are pre- sented and discussed. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction In recent years, research on the methods for heat transfer en- hancement in heat exchangers has received great attention in order to cater for the growing needs of higher efficiencies in these devices. Corrugated surface geometry is one of the many suitable techniques to enhance the heat transfer in heat exchangers. When fluid flows in a corrugated channel, the flow becomes disturbed due to growing recirculation regions near the corrugated wall, which enhances the mixing of fluid as well as heat transfer. On the coolant side, the use of nanofluids, a liquid in which nanoparticles are added to a base fluid, can also enhance the heat transfer due to the improved thermal conductivity of the fluid. Many researchers have investigated flow and heat transfer of con- ventional fluid through corrugated channel numerically and experi- mentally. Wang and Chen [1] studied numerically the forced convection in a channel with a wavy wall. The spine alternating direc- tion implicit method was applied to determine the flow and heat transfer characteristic. They found that the heat transfer enhance- ment was significant at larger amplitude wavelength ratio, especially at higher Reynolds numbers. Sawyers et al. [2] combined the analyti- cal and the numerical techniques to study the effect of three- dimensional hydrodynamics on the enhancement of heat transfer in corrugated channel. They observed that in three-dimensional case, a small mean flow in the transverse direction leads to increase in the heat transfer, while there is decrease in heat transfer as the transverse flow becomes stronger. Fabbri [3] studied the convective heat transfer in a channel composed of smooth and corrugated walls under laminar flow conditions. The velocity and temperature distributions were de- termined using the finite element method. It was found that the rela- tive improvements in heat transfer of the optimum corrugated profile increase with the Reynolds and Prandtl numbers. Islamoglu and Par- maksizoglu [4] experimentally studied the effect of channel height on the enhanced heat transfer characteristics for air flowing in a corru- gated heat exchanger channel. They found that the Nusselt number and the friction factor increase but the pressure gradient decreases with the increase in channel height. Islamoglu and Kurt [5] employed an artificial neural network formulation to analyze the heat transfer in corrugated channels. Results indicated that the artificial neural net- work model could be trained to provide satisfactory estimations of Nusselt numbers for air flow in corrugated channels. Fabbri and Rossi [6] considered the effects of entrance region of a channel composed by a corrugated profile and a flat wall on the heat transfer. The governing equations were solved using the finite- element method. They observed that the heat transfer was effectively enhanced as the amplitude of the corrugated profile and the Reynolds number increased. Metwally and Manglik [7] studied numerically the laminar periodically developed forced convection in sinusoidal corrugated-plate channels. Results showed that the mixing produced by these self-sustained transverse vortices significantly enhances the heat transfer depending upon the Reynolds and Prandtl numbers as well as the channel corrugation aspect ratios. The enhancement was found to come with a relatively small friction factor penalty. Mohamed et al. [8] numerically studied the effects of the entrance re- gion of a symmetric wavy-channel on the heat transfer and flow field. It was found that the shear stress and the Nusselt number increase International Communications in Heat and Mass Transfer 38 (2011) 1368–1375 ☆ Communicated by W.J. Minkowycz. ⁎ Corresponding author. E-mail address: hafeez@uniten.edu.my (N.H. Shuaib). 0735-1933/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.icheatmasstransfer.2011.08.013 Contents lists available at SciVerse ScienceDirect International Communications in Heat and Mass Transfer journal homepage: www.elsevier.com/locate/ichmt