A numerical study on dynamic inertial focusing of microparticles in a confined flow

Inertial microfluidics is regarded as a promising approach to facilitate precise, robust and continuous manipulation of particles through inertial focusing of particles in microchannels. Although there is a need to gain rich insights into the focusing dynamics of particles, it has been hardly studied numerically. In this study, the complex focusing dynamics of particles is simulated numerically for multi-particle suspensions in confined microchannels. To this end, we develop a new method that couples the discrete element method (DEM) with the direct numerical simulation (DNS). This method is referred to as the DEM–DNS method. In order to validate the DEM–DNS method, we then investigate complex dependence of particle behaviour on Reynolds number and channel geometries. With good agreement between the numerical results and existing observations, it is shown for the first time that the DEM–DNS method can simulate the counterintuitive focusing dynamics of particles. This study thus establishes that the DEM–DNS method is a powerful tool to examine the focusing dynamics of particles in inertial microfluidics.

[1]  Steven W Graves,et al.  Inertial manipulation and transfer of microparticles across laminar fluid streams. , 2012, Small.

[2]  Elisabeth Guazzelli,et al.  Trains of particles in finite-Reynolds-number pipe flow , 2004 .

[3]  Elisabeth Guazzelli,et al.  Inertial migration of rigid spherical particles in Poiseuille flow , 2004, Journal of Fluid Mechanics.

[4]  S. Luding,et al.  Rheology of weakly wetted granular materials: a comparison of experimental and numerical data , 2013, 1404.0318.

[5]  Seiichi Koshizuka,et al.  Lagrangian–Lagrangian modeling for a solid–liquid flow in a cylindrical tank , 2012 .

[6]  Y. Tsuji,et al.  Discrete particle simulation of two-dimensional fluidized bed , 1993 .

[7]  D. Weitz,et al.  Axial and lateral particle ordering in finite Reynolds number channel flows , 2009 .

[8]  James R. Percival,et al.  Verification and validation of a coarse grain model of the DEM in a bubbling fluidized bed , 2014 .

[9]  Derek B. Ingham,et al.  Laminar boundary layer on an impulsively started rotating sphere , 1979 .

[10]  Pascale Magaud,et al.  Migration of finite sized particles in a laminar square channel flow from low to high Reynolds numbers , 2014 .

[11]  Mehmet Toner,et al.  Inertial focusing in microfluidics. , 2014, Annual review of biomedical engineering.

[12]  H. Lugt,et al.  Laminar flow behavior under slip−boundary conditions , 1975 .

[13]  A. Ladd,et al.  Inertial migration of neutrally buoyant particles in a square duct: An investigation of multiple equilibrium positions , 2006 .

[14]  Xiaosong Sun,et al.  Three-dimensional simulation of gas–solid–liquid flows using the DEM–VOF method , 2015 .

[15]  G. Segré,et al.  Radial Particle Displacements in Poiseuille Flow of Suspensions , 1961, Nature.

[16]  K. T. Tsang,et al.  Mirror stability of a hot electron ring plasma , 1983 .

[17]  Xiaosong Sun,et al.  A Lagrangian–Lagrangian coupled method for three-dimensional solid–liquid flows involving free surfaces in a rotating cylindrical tank , 2014 .

[18]  Jian Zhou,et al.  Fundamentals of inertial focusing in microchannels. , 2013, Lab on a chip.

[19]  T. Itano,et al.  Inertial migration of neutrally buoyant spheres in a pressure-driven flow through square channels , 2014, Journal of Fluid Mechanics.

[20]  T. Kajishima,et al.  Turbulence Structure of Particle-Laden Flow in a Vertical Plane Channel Due to Vortex Shedding , 2001 .

[21]  T. Zhao,et al.  Investigation of granular batch sedimentation via DEM–CFD coupling , 2014 .

[22]  Xingyu Jiang,et al.  Inertial focusing of spherical particles in rectangular microchannels over a wide range of Reynolds numbers. , 2015, Lab on a chip.

[23]  N. Patankar,et al.  Direct numerical simulation of the Brownian motion of particles by using fluctuating hydrodynamic equations , 2004 .

[24]  H. Stone,et al.  Particle segregation and dynamics in confined flows. , 2009, Physical review letters.

[25]  R. Tompkins,et al.  Continuous inertial focusing, ordering, and separation of particles in microchannels , 2007, Proceedings of the National Academy of Sciences.

[26]  P. Cundall,et al.  A discrete numerical model for granular assemblies , 1979 .