Dynamics of rotating paramagnetic particles simulated by lattice Boltzmann and particle dynamics methods

Abstract

Novel biochemical sensors consisting of rotating chains of microscale paramagnetic particles have been proposed that would enable convenient, sensitive analyte detection. Predicting the dynamics of these particles is required to optimise their design. The results of lattice Boltzmann (LB) and particle dynamics (PD) simulations are reported, where the LB approach provides a verified solution of the complete Navier-Stokes equations, including the hydrodynamic interactions among the particles. On the other hand, the simpler PD approach neglects hydrodynamic interactions, and does not compute the fluid motion. It is shown that macroscopic properties, like the number of aggregated particles, depend only on the drag force and not on the total hydrodynamic force, making PD simulations yield reasonably accurate predictions. Relatively good agreement between the LB and PD simulations, and qualitative agreement with experimental data, are found for the number of aggregated particles as a function of the Mason number. The drag force on a rotating cylinder is significantly different from that on particle chains calculated from both simulations, demonstrating the different dynamics between the two cases. For microscopic quantities like the detailed force distributions on each particle, the complete Navier-Stokes solution, here represented by the LB simulation, is required.

Numerical and experimental study of a rotating magnetic particle chain in a viscous fluid

“…6, the observed R T c is plotted as a function of the bead chain length. Experimentally, Micromer particles (due to their low magnetic susceptibility) form short bead chains (5-10 particles) whereas Dynabeads form relatively long bead chains (11)(12)(13)(14)(15)(16)(17) particles). Numerically ( Fig.…”

“…Rotational dynamics of isolated magnetic particle chains have also been studied extensively [10][11][12][13]. The rotating chains are observed to undergo a process of dynamic growth and fragmentation that is dependent on the frequency of the applied field.…”

“…Typical structures such as linear chains and S-shaped chains are noted. Yadav et al [12] and Krishnamurthy et al [13] observed that the particle dynamics method is able to predict the macroscopic chain dynamics accurately. But, for microscopic properties, inclusion of hydrodynamic interactions becomes important.…”

Dynamics of rotating paramagnetic particle chains simulated by particle dynamics, Stokesian dynamics and lattice Boltzmann methods

“…The dynamics of these fluids under various conditions are still not completely understood, and more powerful dynamic simulation tools are required for their successful application to a variety of situations. Although there have been many previous simulations of MR fluids (Martin 2001;Melle et al 2003;Yadav et al 2006), most of these studies employed a simplified approach to the modeling of fluid flow (such as neglecting hydrodynamic interactions between particles), and a simple Stokes drag was used to calculate the velocities. This approach is referred to here as the particle dynamics (PD) method.…”

“…This approach is referred to here as the particle dynamics (PD) method. For a detailed analysis, the reader can refer to Martin (2001), Melle et al (2003), andYadav et al (2006).…”