Self-assembly of silica microparticles in magnetic multiphase flows: Experiment and simulation

Abstract

Dynamic self-assembly, especially self-assembly under magnetic field, is vital not only for its marvelous phenomenon but also for its mechanisms. Revealing the underlying mechanisms is crucial for a deeper understanding of self-assembly. In this paper, several magnetic induced self-assembly experiments by using the mixed magnetic multiphase fluids comprised of silica microspheres were carried out. The relations of the strength of external magnetic field, the inverse magnetorheological effect, and the structures of self-assembled particles were investigated. In addition, a momentum-exchanged immersed boundary-based lattice Boltzmann method (MEIB-LBM) for modeling multi-physical coupling multiphase flows was employed to numerically study the magnetic induced self-assembly process in detail. The present work showed that the external magnetic field can be used to control the form of self-assembly of nonmagnetic microparticles in a chain-like structure, and the self-assembly process can be classified into four stages with magnetic hysteresis, magnetization of nonmagnetic microparticles, self-assembly in chain-like structures, and the stable chain state. The combination of experimental and numerical results could offer a method to control the self-assembled nonmagnetic microparticles, which can provide the technical and theoretical support for the design and fabrication of micro/nanomaterials.

Effect of self-assembly on fluorescence in magnetic multiphase flows and its application on the novel detection for COVID-19

“…To approach these problems, a technique of noncontact manipulation in micro/nanoscale, i.e., the magnetic field induced self-assembly in magnetic multiphase flows, 11–22 is adopted in this work, which could manipulate the micro/nanoparticles by applying an external magnetic field. Self-assembly has been proved as a prospective, powerful, and controllable technique in building micro/nanostructures, which is widely used in microsensors, heat transfer devices, biomedicines, and targeted drugs.…”

Motion, deformation, and coalescence of ferrofluid droplets subjected to a uniform magnetic field

“…Several techniques have been developed in the past few decades, such as the VOF method, 31 LS method, 32 front tracking method, 33 and phase-field method. [34][35][36] The original VOF method has the property of excellent mass conservation but it suffers from the accurate reconstruction of interface because the interface is based only on the volume fraction of fluid. On the other hand, the original LS method can track the interface accurately, but it cannot preserve the mass conservation.…”

“…Interface capturing is crucial in the simulation of complicated multiphase problems, especially when the interface is moving. Several techniques have been developed in the past few decades, such as the VOF method, 31 LS method, 32 front tracking method, 33 and phase‐field method 34‐36 . The original VOF method has the property of excellent mass conservation but it suffers from the accurate reconstruction of interface because the interface is based only on the volume fraction of fluid.…”

Modeling of mass transfer enhancement in a magnetofluidic micromixer

“…Parada and Zimmerman (2006) used a magnetohydrodynamic model to analyse the interaction of a conductive fluid in both electric and magnetic fields using Galerkin finite element method (FEM). Li et al (2018) conducted several experiments on magnetic induced self-assembly using mixed magnetic multiphase fluids comprised of silica microspheres. Chen et al (2017) employed a multi-physics numerical model to investigate the sedimentation of two non-magnetic particles in a magnetic fluid subjected to a magnetic field.…”