Numerical and experimental investigations of the formation process of ferrofluid droplets

Abstract

This paper reports both experimental and numerical investigations of the formation process of ferrofluid droplets in a flow focusing configuration with and without an applied magnetic field. In the experiment, the homogenous magnetic field was generated using an electromagnet. The magnetic field in the flow direction affects the formation process and changes the size of the droplets. The change in the droplet size depends on the magnetic field strength and the flow rates. A numerical model was used to investigate the force balance during the droplet breakup process. A linearly magnetizable fluid was assumed. Particle level set method was employed to capture the interface movement between the continuous fluid and the dispersed fluid. Results of the droplet formation process and the flow field are discussed for both cases with and without the magnetic field. Finally, experimental and numerical results are compared.

Droplet Merging on a Lab-on-a-Chip Platform by Uniform Magnetic Fields

“…4b). This value is higher than the value of 12 mN/m for ferrofluid-silicone oil interfacial tension without magnetic field64.…”

“…The above challenges can be addressed by a combination of magnetic fluids and uniform magnetic fields, which offers a wireless, programmable and remote method to perform LoC operations. In the literature uniform magnetic field was used on LoC platforms to investigate ferrohydrodynamic instabilities in uniform magnetic field6162, FFD formation6364, non-linear deformation of FFD65, magnetic trapping of bacteria66, magnetofluidic mixing67, and spreading68.…”

Theoretical modeling in microscale locomotion

“…SBT is then further developed to analyze the behavior of flagellum or filament by adding the contributions of higher order singularities (Johnson 1980). When used to compute the swimming velocity of a helical swimmer, Lighthill's and Johnson's SBT actually provides very similar results regardless of the helix pitch angle (Liu et al 2011). For organisms with negligible rotational velocity, the flagellum can be replaced by a distribution of Stokeslets and doublets along the centerline with force per unit length point f(s) and d(s), respectively, in order to satisfy the no slip on the surface of the flagellum.…”

Model-based Adjustment of Droplet Characteristic for 3D Electronic Printing

“…One of most typical methods is using numerical techniques to model the DoD piezoelectric inkjet printhead [4], which focuses on the liquid filament volition of droplet…”