Field-controlling patterns of sheared ferrofluid droplets

Abstract

We investigate how ferrofluid droplets suspended in a wall-bounded shear flow can organise when subjected to an external magnetic field. By tuning the magnitude of the external magnetic field, we find that the ferrofluid droplets form chain-like structures in the flow direction when the magnetic field is weak, while forming a crystal-like pattern in a strong magnetic field. We provide the phase diagram and the critical conditions for this chain-to-crystal transition, by applying both numerical simulations and analytic calculations. We also examine how the organised patterns of the ferrofluid droplets can be controlled by simply changing the direction of the magnetic field. This work demonstrates new aspects of field-controllable ferrofluid droplets as a configurable and reprocessable metamaterial.

12012 fundamental mechanisms behind nanotechnology applications in oil and gas: Emerging nano-EOR processes

“…However, Wang et al developed a 3D model based on volume of fluid method and predicted the prohibits the oil recovery when the magnetic field direction is transverse to the flow direction, which is in contrary to their experimental results, hinting the presence of other mechanisms (Wang et al, 2021), (Wang et al, 2020). Magnetic nanoparticles form temporal micro-structures when exposed to external disturbances of either magnetic fields (Robbes et al, 2011), (Tracy and Crawford, 2013) or shears (Ishida et al, 2021), as shown in Figure 15. These micro-structures can be permanentized by solidifying the fluid (Tracy and Crawford, 2013).…”