Abstract
As the chains composed of magnetic particles (MPs) move through a channel, the breaking, recomposing, and sticking to the channel wall of the chains may occur, and it is of great importance to reveal the motion regularity of magnetic nanoparticles when they are used as carriers. In this work, experimental visualizations and numerical simulations were carried out to investigate the bending phenomena of different types of chains composed of micro-sized magnetic particles in a channel flow governed by a transversal magnetic field. The experiments focus on the motion of the MP chain, and different types of chains were observed and photographed. In addition, the pose of the chains was investigated based on the lattice Boltzmann method (LBM) by using particles with diameter equal to the thickness of the chain. It is revealed that as the inlet velocity of carrier fluid increases, the bending degree of the chain increases and the regularities well coincide with the LBM simulation results. The shear force on the end particle was taken to evaluate the stability of the chain. In addition, the reorganization process of two short chains was investigated. It is feasible to model the chain composed of micro-sized MPs with large particles so as to predict the motion regularity of the chains efficiently.
Highlights
Since the integrity of chains can be ensured during flow process, to reduce simulation workload, we proposed a simplified modeling method, i.e., the large particles with the diameter equal to the thickness of the chain were used in lattice Boltzmann method (LBM) simulation
Experimental visualization was carried out for the chains composed of micro-sized magnetic particles moving in a circular microchannel
The LBM simulations were carried out to predict the pose of different types of chains, and the computational efficiency is greatly improved by using the particles with diameter that equals the chain thickness
Summary
Magnetorheological Fluid (MRF) is a suspension consisting of a mixture of tiny soft magnetic particles (MPs) with high magnetic permeability and non-magnetic conductive liquids, which has extremely high research and application values. Nowadays, MRF has been applied in many fields such as lubrication, mechanical seal, mineral processing, magnetic circuits, biological separation, magnetic resonance imaging, and biomedical research. Under the action of an external magnetic field, the particles in the magnetorheological suspension acquire dipole moments and aggregate in the direction of the magnetic field to form a chain. The structure of the chain hinders the flow of the carrier fluid, thereby imparting a certain solid characteristic to the magnetorheological fluid, which is the basis for the magnetorheological characteristics.13In the recent years, excellent works on the aggregation process that takes place before the MPs are chained under an external magnetic field have been carried out. researchers pay more attention on the spin of chains after particles aggregate into chains, but less attention on the solid–liquid two-phase flow of the carrier liquid and MP chains. Magnetorheological Fluid (MRF) is a suspension consisting of a mixture of tiny soft magnetic particles (MPs) with high magnetic permeability and non-magnetic conductive liquids, which has extremely high research and application values.. MRF has been applied in many fields such as lubrication, mechanical seal, mineral processing, magnetic circuits, biological separation, magnetic resonance imaging, and biomedical research.. Under the action of an external magnetic field, the particles in the magnetorheological suspension acquire dipole moments and aggregate in the direction of the magnetic field to form a chain.. Excellent works on the aggregation process that takes place before the MPs are chained under an external magnetic field have been carried out.. Researchers pay more attention on the spin of chains after particles aggregate into chains, but less attention on the solid–liquid two-phase flow of the carrier liquid and MP chains.
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