Motion Of Multiple Particles Research Articles

A phase‐field based model for coupling two‐phase flow with the motion of immersed rigid bodies

AbstractThe interaction of immersed rigid bodies with two‐phase flow is of high interest in many applications. A model for the coupling of a Hohenberg–Halperin type model for two‐phase flow and a fictitious domain method for consideration of rigid bodies is introduced leading to a full multiphase‐field method to address the overall problem. A normalized phase variable is used alongside a method for application of wetting boundary conditions over a diffuse fluid‐solid interface. This enables the representation of capillary effects and different wetting behavior based on Young's law. A number of simulations is conducted in order to validate the model and highlight its ability to handle a variety of setups for two‐phase particulate flow. This includes dynamic wetting situations, the motion of multiple particles within the two‐phase flow and the interaction with arbitrarily shaped solid structures inside the domain.

Motion of paramagnetic particles in a viscous fluid under a uniform magnetic field: benchmark solutions

Numerical simulations of the two-dimensional motion of multiple paramagnetic particles suspended in a viscous fluid subjected to a uniform magnetic field are presented. Both the magnetic field and flow field can be described efficiently with simple series in local coordinates attached to each particle. The coefficients of the series can be obtained with fast convergence when only a few leading coefficients are treated implicitly. Numerical results for the flow field are validated by comparing the data with those given by an asymptotic solution for a pair of particles separated by a small distance. The numerical results of the magnetic field are validated by comparison with the solutions in bipolar coordinates. Simulations of the motion of multiple particles reveal interesting phenomena and shed light on the fundamental mechanism of particles clustering into a straight chain. The data presented in this paper can be used as a benchmark solution for verifying codes for simulating the motion of paramagnetic particles in a magnetic field.

Dependence of fragmentation behavior of colloidal aggregates on their fractal structure

The fragmentation dynamics of aggregate of non-Brownian particles in shear flow is investigated numerically. The breakup behaviors of aggregates having the same connectivity but the different space-filling properties are examined. The Lagrangian particle simulation in a linear flow field is performed. The effect of surrounding fluid on the motion of multiple particles is estimated by Stokesian dynamics approach. The inter-particle force is calculated from the retarded van der Waals potential based on the Lifshitz theory. The results obtained in this work indicate that the fragmentation behavior of colloidal aggregates depends on their fractal structure. However, if the resultant aggregate size is smaller than the critical one, the fragmentation behavior shows the universality regardless of their original structure. Furthermore, the restructuring of aggregate in shear flow and its effect on the fragmentation process are also discussed.

1343 粒子配位相似則モデルによるギガスケール DEM シミュレーション

A novel method for giga-scale DEM simulation was derived. The method is based on the motion equation for particles keeping the local particle assembly similar. The motion of multiple particles whose diameter, density and chemical composition are the same is represented by one particle called a representative particle. This method can be accordingly called'a representative particle model'. A representative particle occupies the same volume as the one of the represented particles and has the same density and chemical composition. This model can be applied even for cohesive particles and non-uniform size particles. The present model was validated by carrying out numerical simulations for particles of 2 densities. From the comparisons between the results with and without the model, the effectiveness of the model was confirmed.