Simulation of oscillation of magnetic particles in 3D microchannel flow subjected to alternating gradient magnetic field

Abstract

Abstract Magnetic particles (MPs) have good response to external magnetic field. To investigate the motion regularity of MPs in a mcirochannel flow governed by alternating gradient magnetic field, a 3D numerical simulation method is established based on the lattice Boltzmann method (LBM) and the immersed boundary method (IBM). The motions of both a single MP and a short chain of MPs are investigated and each is found to be a superposition of transverse oscillation and longitudinal translation. By performing a simple filtering processing for the original trajectory of MP, it is revealed that the oscillation of MPs affected by alternating gradient magnetic field can be characterized as the simple harmonic vibration. The oscillation frequency of MPs is basically in accordance with the alternating frequency of the gradient magnetic field in the range from 400 to 800 Hz. The larger magnetic field gradient results in the larger amplitude of oscillation. The wavelength of the trajectory is increased due to the increasing inlet velocity of carrier fluid. For the MP chain, both the period and amplitude of oscillation will decrease with the increase of alternating frequency of magnetic field. The turbulence intensity distribution indicates that the turbulence of microchannel flow can be enhanced by the oscillation of MPs thus enhance the mass or heat transfer in the carrier fluid.