Vol.:(0123456789) 1 3 Journal of the Brazilian Society of Mechanical Sciences and Engineering (2019) 41:237 https://doi.org/10.1007/s40430-019-1734-7 TECHNICAL PAPER Numerical investigation of FHD pump for pumping the magnetic nanofuid inside the microchannel with hydrophobic walls Saber Yekani Motlagh 1  · Mohammad Mehdizadeh Youshanloei 1  · Taha Safabakhsh 1 Received: 13 September 2018 / Accepted: 16 April 2019 © The Brazilian Society of Mechanical Sciences and Engineering 2019 Abstract In this paper, pumping of water-based magnetic nanofuid of Fe 3 O 4 by the Kelvin force due to the non-uniform magnetic feld inside the microchannel with hydrophobic walls is numerically studied. The magnetic feld of permanent magnet is used as a magnetic source. The governing equations are derived from the addition of the Kelvin body force to the momen- tum equations, which are discretized by the fnite volume along with PISO algorithm. To study the parameters afecting the performance of the magnetic nanofuid micropump, slip length of walls, the nanoparticle diameter, volume fraction of the nanoparticles, saturation magnetization of magnet, and width and height of the horizontal and vertical magnets are changed. The results show that increasing each of these parameters leads to an increase in the speed of the fow in microchannel, which is due to the increase in the Kelvin force along the channel. The efect of diameter of the magnetic nanoparticles on the speed of generated fow inside the channel was greater than that of the other parameters. In addition, the vertical magnet causes more speed than the horizontal one. Thermal characteristics of magnetic nanofuid fow have been also investigated by calculation of the temperature in outlet of microchannel. There is a slight increase in temperature due to small efect of magnetocaloric and viscous dissipation efects. Keywords Magnetic nanofuid · Micropump · FHD · Hydrophobic surface · Microchannel · Partial slip 1 Introduction Nanofuid is a branch of mechanical engineering in which aspects of fuids containing nanoparticles are investigated. Due to specifc features (i.e., high specifc heat capacity, magnetism, high thermal conductivity, increased viscos- ity), such fuids are used in various applications. Nanofuids are made of diferent types of nanoparticles with diferent shapes and sizes, thus exhibiting diferent behaviors. Mag- netic nanofuid is a type of nanofuids created by adding magnetic nanoparticles such as iron oxide into the base fuid. Furthermore, some fuids exhibit magnetic behavior naturally. For instance, erythrocytes in blood contain iron; therefore, blood exhibits magnetic behavior. Such fuids are known as biological ferrofuids. The behavior of this type of fuids when exposed to magnetic feld has drawn a lot of attention to itself, and thus, considerable research has been done in regard to this matter; refer to [1] as an example. The need for equipment to store and pump nanofuids is increasing as associated applications develop in indus- tries such as medicine, cooling and heat exchangers. Mag- netic micropumps are one of the equipment that can pump magnetic fuids and generate a continuous fow without direct contact with the fuid. The conventional form of such pumps is the magnetohydrodynamic pumps (MHD) which take advantage of the property of electrical conductivity of the fuid. The Lorentz force created by the magnetic feld, which is volumetrically exerted on the fuid inside the chan- nel, causes the fuid to move. The operation of such pumps depends on the property of electrical conductivity of the fuid; hence, they are applicable for fuids with high electri- cal conductivity. Much research has been done regarding the efective parameters of magnetic nanofuids and magneto- hydrodynamic (MHD) pumps operations. For instance, the performance of MHD micropump using steady, incompress- ible, fully developed and laminar model was investigated by Ho [2]. He converted the Lorentz force into hydrostatic Technical Editor: Jader Barbosa Jr., Ph.D. * Saber Yekani Motlagh s.yekani@uut.ac.ir; syekani@yahoo.com 1 Department of Mechanical Engineering, Urmia University of Technology (UUT), P.O. Box 57166-419, Urmia, Iran