Aggregation and flow behavior of magnetic particles in microchannel flow governed by a transverse magnetic field

Abstract

Magnetic particles (MPs) can be used as carriers for intentionally transporting medium with the effect of external magnetic field. To reveal the aggregation and transportation regularity of magnetic particles in microchannel flow, the three-dimensional (3D) and two-phase lattice Boltzmann method combined by both the immersed boundary method and the discrete element method is established and the investigation on the evolution of chain-like structure composed of MPs in a microchannel flow governed by transverse uniform magnetic field is investigated. It is revealed MPs can maintain the chain-like structure in the channel flow due to the magnetic dipole force, and the final postures of MP chains are determined by the coupling effect of the base fluid and the chains. The average velocity of the MPs moving in the form of chains is smaller than that moving as discrete elements and the velocity of near-wall fluid is increased. Being a cohesive force, if magnetic dipole force is not large enough, the chain-like structure will be broken due to the push of base fluid with velocity gradient. It is also found that there exists a critical value of the intensity of magnetic dipole force for MPs to maintain the chain-like structure in a microchannel flow with the given inlet velocity. This work demonstrates that, under transverse uniform magnetic field, the discrete MPs can be transported as an entirety in microchannel flow on the promise that the magnetic dipole force is large enough to hold the MPs in the flow field with velocity gradient.