Numerical investigation on the effect of external varying magnetic field on the mixing of ferrofluid with deionized water inside a microchannel for lab-on-chip systems
Milad Saadat, Majid Ghassemi, Mohammad Behshad Shafii
Abstract
Energy-efficient mixing is vital for chemical and fuel processes. To this end, a flow-focusing configuration is proposed to investigate the effect of a uniform magnetic field on the mixing of a water-based ferrofluid with two streams of deionized water. An external and varying magnetic field is imposed on a straight microchannel, and the mixing between the ferrofluid and deionized waters is qualitatively and quantitatively measured. A commercial code based on the finite-element method is used, and the simulations are validated by two experimental studies in the literature. For a magnetic flux density of 10 mT, a signal frequency of 1 Hz, a duty cycle of 0.3, an inlet velocity of 500 µm/s, and a relative inlet velocity of 0.5, an excellent mixing efficiency as high as 97.4 % is achieved after 1.5 s of the magnetic actuation. This model benefits from its low implementation cost and can help augment and develop energy-efficient lab-on-chip platforms.