Clustering of Charged Inertial Particles in Turbulence

Lu, Jiang; Saw, Ewe-Wei; Shaw, Raymond A.

doi:10.1103/physrevlett.104.184505

Cited by 66 publications

(86 citation statements)

References 14 publications

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“…St k is the Stokes number, the ratio of the particle relaxation timescale τ p to the Kolmogorov timescale τ η . The experimental measurements of Lu et al 36 clearly demonstrate that the exponential rise of the RDF is suppressed by the charging of particles. The charging introduces a length scale below which clustering of particles is suppressed.…”

Section: Introductionmentioning

confidence: 92%

“…Alipchenkov et al 35 have suggested a statistical model to explain clustering of charged particles in isotropic turbulence. Lu et al 36 reported measurements of clustering of charged particles in isotropic turbulence. It has been observed that the RDF increases exponentially at sub-Kolmogorov scales for uncharged particles and this power law behaviour has been explained by Chun et al 37 …”

Section: Introductionmentioning

confidence: 99%

“…They also extended the theoretical framework developed by Chun et al 37 to include the "drift" due to Coulomb repulsion force between pair of particles. The functional form of the RDF for charged particles as derived by Lu et al 36 results from a balance between the outward drift due to Coulomb repulsion and inward drift due to inertia and is as follows:…”

Section: Introductionmentioning

confidence: 99%

“…The limits Lu et al 36 chose to apply are also applied here with one exception. The exception is St k 1: we simulate a range of St k up to ∼40.…”

Section: Introductionmentioning

confidence: 99%

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Mitigation of preferential concentration of small inertial particles in stationary isotropic turbulence using electrical and gravitational body forces

Karnik¹,

Shrimpton²

2012

Physics of Fluids

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Particles with a certain range of Stokes numbers preferentially concentrate due to action of turbulent motion and body forces such as gravity are known to influence this process. The effect of electric charge, residing on particles, upon the phenomenon of preferential concentration is investigated. We use direct numerical simulations of oneway coupled stationary isotropic turbulence over a range of particle Stokes numbers, fluid Taylor Reynolds numbers, and electrical and gravitational particle body force magnitudes, the latter characterized by non-dimensional settling velocities, v * c and v * g , respectively. In contrast to the gravitational body force, the electrical analogue, acting on an electrically charged particle, is generated by an electric field, which is in turn a function of the degree of preferential concentration. Thus, the electrical body force is created by, and mitigates, preferential concentration. In the absence of gravity, it is estimated that v * c ≈ 1.0 is sufficient to homogenise a preferentially concentrated particle distribution. It is seen that charging drastically reduces the radial distribution function values at Kolmogorov scale separations, which gravitational force does not. This implies that charging the particles is an efficient means to destroy small clusters of particles. On incorporating the gravitational force, the amount of charge required to homogenise the particle distribution is reduced. It is estimated that v * c ≈ 0.6 is sufficient to homogenise particle distribution at v * g = 2.0. This estimation is corroborated by several different indicators of preferential concentration, and the results also agree reasonably well with corresponding experiments reported in literature. Calculations also suggest that sprays generated by practical charge injection atomizers would benefit from this electrical dispersion effect. C 2012 American Institute of Physics. [http://dx.A. U. Karnik and J. S. Shrimpton Phys. Fluids 24, 073301 (2012) * c Re λ = 24.2 Re λ = 45.0 Re λ = 80.6 FIG. 6. Electrical force normalised by drag force averaged over all the particles for St k = 1.0 particles at different nondimensional Coulomb velocities and Reynolds numbers.

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Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The limits Lu et al 36 chose to apply are also applied here with one exception. The exception is St k 1: we simulate a range of St k up to ∼40.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mitigation of preferential concentration of small inertial particles in stationary isotropic turbulence using electrical and gravitational body forces

Karnik¹,

Shrimpton²

2012

Physics of Fluids

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“…Those parameters are usually determined by direct numerical simulation (DNS) data. Data from laboratory experiments (Saw et al 2008;Lu et al 2010;Bordas et al 2011) would, of course, help, but available data are very limited.…”

Section: Introductionmentioning

confidence: 97%

Collision statistics of inertial particles in two-dimensional homogeneous isotropic turbulence with an inverse cascade

Onishi

Vassilicos

2014

J. Fluid Mech.

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This study investigates the collision statistics of inertial particles in inverse-cascading two-dimensional (2D) homogeneous isotropic turbulence by means of a direct numerical simulation (DNS). A collision kernel model for particles with small Stokes number (St) in 2D flows is proposed based on the model of Saffman & Turner (J. Fluid Mech., vol. 1, 1956, pp. 16-30) (ST56 model). The DNS results agree with this 2D version of the ST56 model for St 0.1. It is then confirmed that our DNS results satisfy the 2D version of the spherical formulation of the collision kernel. The fact that the flatness factor stays around 3 in our 2D flow confirms that the present 2D turbulent flow is nearly intermittency-free. Collision statistics for St = 0.1, 0.4 and 0.6, i.e. for St < 1, are obtained from the present 2D DNS and compared with those obtained from the three-dimensional (3D) DNS of Onishi et al. (J. Comput. Phys., vol. 242, 2013, pp. 809-827). We have observed that the 3D radial distribution function at contact (g(R), the so-called clustering effect) decreases for St = 0.4 and 0.6 with increasing Reynolds number, while the 2D g(R) does not show a significant dependence on Reynolds number. This observation supports the view that the Reynolds-number dependence of g(R) observed in three dimensions is due to internal intermittency of the 3D turbulence. We have further investigated the local St, which is a function of the local flow strain rates, and proposed a plausible mechanism that can explain the Reynolds-number dependence of g(R). Meanwhile, 2D stochastic simulations based on the Smoluchowski equations for St 1 show that the collision growth can be predicted by the 2D ST56 model and that rare but strong events do not play a significant role in such a small-St particle system. However, the probability density function of local St at the sites of colliding particle pairs supports the view that powerful rare events can be important for particle growth even in the absence of internal intermittency when St is not much smaller than unity.

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Introduction

Chen

2023

Microparticle Dynamics in Electrostatic and Flow Fields

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Clustering of Charged Inertial Particles in Turbulence

Cited by 66 publications

References 14 publications

Mitigation of preferential concentration of small inertial particles in stationary isotropic turbulence using electrical and gravitational body forces

Mitigation of preferential concentration of small inertial particles in stationary isotropic turbulence using electrical and gravitational body forces

Collision statistics of inertial particles in two-dimensional homogeneous isotropic turbulence with an inverse cascade

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