scholarly journals Research on the Inertial Migration Characteristics of Bi-Disperse Particles in Channel Flow

2021 ◽  
Vol 11 (19) ◽  
pp. 8800
Author(s):  
Dongmei Chen ◽  
Jianzhong Lin ◽  
Xiao Hu
Keyword(s):  
Engineering Practice ◽  
Inertial Focusing ◽  
Inertial Migration ◽  
Particle Spacing ◽  
Focusing Effect ◽  
Blocking Rate ◽  
Application Potential ◽  
Initial Spacing ◽  
Boltzmann Method ◽  
Final Spacing

The inertial focusing effect of particles in microchannels shows application potential in engineering practice. In order to study the mechanism of inertial migration of particles with different scales, the motion and distribution of two particles in Poiseuille flow are studied by the lattice Boltzmann method. The effects of particle size ratio, Reynolds number, and blocking rate on particle inertial migration are analyzed. The results show that, at a high blocking rate, after the same scale particles are released at the same height of the channel, the spacing between the two particles increases monotonically, and the change in the initial spacing has little effect on the final spacing of inertial migration. For two different size particles, when the smaller particle is downstream, the particle spacing will always increase and cannot remain stable. When the larger particle is downstream, the particle spacing increases firstly and then decreases, and finally tends to be stable.

scholarly journals Inertial focusing of finite-size particles in microchannels

2018 ◽  
Vol 840 ◽  
pp. 613-630 ◽  
Author(s):  
Evgeny S. Asmolov ◽  
Alexander L. Dubov ◽  
Tatiana V. Nizkaya ◽  
Jens Harting ◽  
Olga I. Vinogradova
Keyword(s):  
Lattice Boltzmann ◽  
Slip Velocity ◽  
Lift Force ◽  
Finite Size ◽  
Reynolds Numbers ◽  
Velocity Difference ◽  
Inertial Focusing ◽  
Inertial Migration ◽  
Lattice Boltzmann Simulations ◽  
Insight Into

At finite Reynolds numbers, $Re$, particles migrate across laminar flow streamlines to their equilibrium positions in microchannels. This migration is attributed to a lift force, and the balance between this lift and gravity determines the location of particles in channels. Here we demonstrate that velocity of finite-size particles located near a channel wall differs significantly from that of an undisturbed flow, and that their equilibrium position depends on this, referred to as slip velocity, difference. We then present theoretical arguments, which allow us to generalize expressions for a lift force, originally suggested for some limiting cases and $Re\ll 1$, to finite-size particles in a channel flow at $Re\leqslant 20$. Our theoretical model, validated by lattice Boltzmann simulations, provides considerable insight into inertial migration of finite-size particles in a microchannel and suggests some novel microfluidic approaches to separate them by size or density at a moderate $Re$.

Simulation of Nanofibers Movement for Near-Field Electrospinning

2009 ◽  
Vol 60-61 ◽  
pp. 456-460 ◽  
Author(s):  
Hong Lian Wang ◽  
Gao Feng Zheng ◽  
Dao Heng Sun
Keyword(s):  
Narrow Range ◽  
Near Field ◽  
Center Of Mass ◽  
Resistance Force ◽  
Mass Center ◽  
Air Resistance ◽  
Movement Distance ◽  
Initial Spacing ◽  
Electric Field Force ◽  
Final Spacing

NFES is a new and simple way to realize precision-positioning of nanofiber. A model on NFES nanofiber movement is built to analyze the effects of the existed nanofibers which have been collected on the substrate, on the nanofiber’s dropping movement. During electrospinning nanofiber is affected by the electric field force, Coulomb repulsive force, air resistance force gravity and so on. The influence of parameters on the deposition behavior of as-spun nanofiber is discussed. The simulation results show that (i) with charge density increasing, the final spacing between mass center of nanofibers A and B (FSAB) increases and the movement distance of center-of-mass of nanofiber B (MDB) decreases first and then increases; (ii) FSAB increases with applied voltage, but decreased in narrow range with concentration of PEO increasing; (iii) FSAB decreased with the initial spacing between mass center of nanofibers A and B (ISAB) increasing, and then it increases after reaching the minimum. So does ISAB to DMB. This simulation model would improve the controlling of nanofiber in NFES.

scholarly journals Direct measurement of particle inertial migration in rectangular microchannels

Lab on a Chip ◽  
2016 ◽  
Vol 16 (15) ◽  
pp. 2840-2850 ◽  
Author(s):  
Kaitlyn Hood ◽  
Soroush Kahkeshani ◽  
Dino Di Carlo ◽  
Marcus Roper
Keyword(s):  
Direct Measurement ◽  
Asymptotic Theory ◽  
Rectangular Microchannels ◽  
Inertial Focusing ◽  
Inertial Migration

We experimentally measured the trajectories of particles undergoing microfluidic inertial focusing, and show that they can be predicted by an asymptotic theory with no unmeasured parameters.

scholarly journals Inertial Migration of Neutrally Buoyant Spherical Particles in Square Channels at Moderate and High Reynolds Numbers

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 198
Author(s):  
Yanfeng Gao ◽  
Pascale Magaud ◽  
Lucien Baldas ◽  
Yanping Wang
Keyword(s):  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Reynolds Numbers ◽  
Spherical Particles ◽  
Particle Volume ◽  
Inertial Focusing ◽  
Inertial Migration ◽  
High Reynolds Numbers ◽  
Micro Channels ◽  
High Reynolds

The inertial migration of particles in microchannel flows has been deeply investigated in the last two decades. In spite of numerous reports on the inertial focusing patterns in a square channel, the particle inertial focusing and longitudinal ordering processes remain unclear at high Reynolds numbers (>200) in square microchannels smaller than 100 µm in width. Thus, in this work, in situ visualization of particles flowing in square micro-channels at Reynolds numbers Re ranging from 5 to 280 has been conducted and their migration behaviors have been analyzed. The obtained results confirm that new equilibrium positions appear above a critical Re depending on the particle to channel size ratio and the particle volume fraction. It is also shown that, for a given channel length, an optimal Reynolds number can be identified, for which the ratio of particles located on equilibrium positions is maximal. Moreover, the longitudinal ordering process, i.e., the formation of trains of particles on equilibrium positions and the characterization of their length, has also been analyzed for the different flow conditions investigated in this study.

scholarly journals Modelling Complex Particle–Fluid Flow with a Discrete Element Method Coupled with Lattice Boltzmann Methods (DEM-LBM)

2020 ◽  
Vol 4 (4) ◽  
pp. 55
Author(s):  
Wenwei Liu ◽  
Chuan-Yu Wu
Keyword(s):  
Discrete Element Method ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Fluid Flows ◽  
Discrete Element ◽  
Dense Particle ◽  
Inertial Migration ◽  
Complex Particle ◽  
Boltzmann Method ◽  
Element Method

Particle–fluid flows are ubiquitous in nature and industry. Understanding the dynamic behaviour of these complex flows becomes a rapidly developing interdisciplinary research focus. In this work, a numerical modelling approach for complex particle–fluid flows using the discrete element method coupled with the lattice Boltzmann method (DEM-LBM) is presented. The discrete element method and the lattice Boltzmann method, as well as the coupling techniques, are discussed in detail. The DEM-LBM is thoroughly validated for typical benchmark cases: the single-phase Poiseuille flow, the gravitational settling and the drag force on a fixed particle. In order to demonstrate the potential and applicability of DEM-LBM, three case studies are performed, which include the inertial migration of dense particle suspensions, the agglomeration of adhesive particle flows in channel flow and the sedimentation of particles in cavity flow. It is shown that DEM-LBM is a robust numerical approach for analysing complex particle–fluid flows.

Numerical Investigation of the Forming and Ordering of Inertially Focused Particle Trains in a Square Microchannel

2019 ◽  
Author(s):  
Shan Wang ◽  
Shanshan Li ◽  
Zhenhai Pan
Keyword(s):  
Cross Sections ◽  
Immersed Boundary Method ◽  
Critical Length ◽  
Immersed Boundary ◽  
Lateral Migration ◽  
Single Particles ◽  
Inertial Focusing ◽  
Micro Channels ◽  
Square Microchannel ◽  
Boltzmann Method

Abstract Inertial focusing of microscale particles has increasingly attracted attentions in various microfluidic applications, such as manipulations of particles/cells, flow cytometry, and highsensitive detection, owing to its passive, robust, and high-throughput nature. While most fundamental studies in literatures have focused on the lateral migration and transverse equilibrium position of single particles in micro-channels with various cross sections, very few of them have dug into the forming and ordering mechanisms of an inertially focused particle train. In this study, the forming inertially focused particle trains are investigated by coupling the lattice Boltzmann method with the immersed boundary method (IB-LBM). The inertial migrations of 6 particles (40 μm in diameter) are simulated in a square microchannel (100 μm in width). The results indicated that the equilibrium axis distance between two neighboring particles is strongly affected by complicated particle-to-particle and particle-to-liquid interactions. Two critical length fractions Lf,c1 and Lf,c2 are observed, which have insignificant effect on balanced distance between two neighboring particles in a particle train.

Computational study of the interaction of freely moving particles at intermediate Reynolds numbers

2012 ◽  
Vol 705 ◽  
pp. 134-148 ◽  
Author(s):  
Açmae El Yacoubi ◽  
Sheng Xu ◽  
Z. Jane Wang
Keyword(s):  
Moving Objects ◽  
Computational Study ◽  
Reynolds Numbers ◽  
Immersed Interface Method ◽  
Immersed Interface ◽  
Particle Spacing ◽  
Simulation Based ◽  
Initial Spacing ◽  
Left And Right ◽  
Freely Moving

AbstractMotivated by our interest in understanding collective behaviour and self-organization resulting from hydrodynamic interactions, we investigate the two-dimensional dynamics of horizontal arrays of settling cylinders at intermediate Reynolds numbers. To simulate these dynamics, we develop a direct numerical simulation based on the immersed interface method. A novel aspect of our method is its ability to efficiently and accurately couple the dynamics of the freely moving objects with the fluid. We report the falling configuration and the wake pattern of the array, and investigate their dependence on the number of particles, $n$, as well as the initial inter-particle spacing, ${d}_{0} $. We find that, in the case of odd-numbered arrays, the middle cylinder is always leading, whereas in the case of even-numbered arrays, the steady-state shape is concave-down. In large arrays $n\geq 5$, the outer pairs tend to cluster. In addition, we analyse detailed kinematics, wakes and forces of three settling cylinders. We find that the middle one experiences a higher drag force in the presence of neighbouring cylinders, compared to an isolated settling cylinder, resulting in a decrease in its settling velocity. For a small initial spacing ${d}_{0} $, the middle cylinder experiences a strong sideway repulsive force, the magnitude of which increases with decreasing ${d}_{0} $. During the fall, the left and right cylinders rotate outwards and shed vortices in anti-phase.

scholarly journals Inertial Focusing and Separation of Particles in Similar Curved Channels

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yue Ying ◽  
Ying Lin
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Particle Separation ◽  
Separation Potential ◽  
Inertial Focusing ◽  
Focusing Effect ◽  
Serpentine Channel ◽  
Curved Channels ◽  
Wave Channel ◽  
High Reynolds

Abstract Inertial particle focusing in curved channels has enormous potential for lab-on-a-chip applications. This paper compares a zigzag channel, which has not been used previously for inertial focusing studies, with a serpentine channel and a square wave channel to explore their differences in terms of focusing performance and separation possibilities. The particle trajectories and fluid fields in the curved channels are studied by a numerical simulation. The effects of different conditions (structure, Reynolds number, and particle size) on the competition between forces and the focusing performance are studied. The results indicate that the zigzag channel has the best focusing effect at a high Reynolds number and that the serpentine channel is second in terms of performance. Regarding the particle separation potential, the zigzag channel has a good performance in separating 5 μm and 10 μm particles at ReC = 62.5. In addition, the pressure drop of the channel is also considered to evaluate the channel performance, which has not been taken into account in the literature on inertial microfluidics. This result is expected to be instructive for the selection and optimization of inertial microchannel structures.

Calmodulin-mediated gating of lens gap junction channels in vesicles

1984 ◽  
Vol 42 ◽  
pp. 134-137
Author(s):  
Camillo Peracchia ◽  
Stephen J. Girsch
Keyword(s):  
Gap Junctions ◽  
Freeze Fracture ◽  
Orthogonal Arrays ◽  
Eye Lens ◽  
Lens Fiber ◽  
Cell Coupling ◽  
Particle Spacing ◽  
Fiber Cells ◽  
Gap Junction Channels ◽  
Communicating Junctions

The fiber cells of eye lens communicate directly with each other by exchanging ions, dyes and metabolites. In most tissues this type of communication (cell coupling) is mediated by gap junctions. In the lens, the fiber cells are extensively interconnected by junctions. However, lens junctions, although morphologically similar to gap junctions, differ from them in a number of structural, biochemical and immunological features. Like gap junctions, lens junctions are regions of close cell-to-cell apposition. Unlike gap junctions, however, the extracellular gap is apparently absent in lens junctions, such that their thickness is approximately 2 nm smaller than that of typical gap junctions (Fig. 1,c). In freeze-fracture replicas, the particles of control lens junctions are more loosely packed than those of typical gap junctions (Fig. 1,a) and crystallize, when exposed to uncoupling agents such as Ca++, or H+, into pseudo-hexagonal, rhombic (Fig. 1,b) and orthogonal arrays with a particle-to-particle spacing of 6.5 nm. Because of these differences, questions have been raised about the interpretation of the lens junctions as communicating junctions, in spite of the fact that they are the only junctions interlinking lens fiber cells.

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