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Moo-Yeon Lee 1 and Jae-Hyeong Seo 2
Academic Editor:Guy Lauriat
1, Department of Mechanical Engineering, Dong-A University, Hadan 840, Saha-gu, Busan 604-714, Republic of Korea
2, Graduate School of Mechanical Engineering, Dong-A University, Hadan 840, Saha-gu, Busan 604-714, Republic of Korea
Received 14 May 2013; Revised 1 October 2013; Accepted 2 October 2013
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
The ferrofluid, which means novel functional fluids using functional materials, has both characteristics of metals and fluids. The ferrofluid generally consisted of magnetite nanosized particle of around 1 to 100 nm and carrier liquid such as water, oils, and hydrocarbons with the aid of surfactants in a continuous carrier phase. It can be controlled by both magnitude and direction of an external magnetic field and temperature [1-12]. In addition, because of the nanosized magnetic particles consisting of the ferrofluids and the surfactant attached to magnetic particles, the ferrofluid could be prevented from particles sticking to each other or precipitate with Brownian motion [2]. Therefore, the ferrofluid could be applied for various industrial fields: enhancement and depression of the heat transfer of the thermal devices, magnetic sealing, damping and bearing of machines, energy conversion system, drug delivery for disease curing, optical devices, micro-/nanofluidic devices, and so forth [3-5].
Numerous numerical and experimental studies have been widely investigated scientifically for various scopes of application. Horng et al. [3] reported the structural pattern formation of the magnetic columns in the ferrofluid thin film under magnetic fields and framework of the application of the ferrofluid based on the remarkable optical properties caused by these magnetically induced structures. Wang et al. [6] studied the effects of magnetic force on the natural convection in porous enclosure under magnetic field. They explained the heat and flow characteristics on the effect of the inclination angle, Darcy number, and magnetic force parameter. Basak et al. [7] analyzed the heat flow due to natural convection within porous trapezoidal enclosures with hot bottom wall and cold side walls in presence of insulated top walls. They examined the thermal mixing within the cavity for various material processing applications and suggested the generalized...