Preferential concentration of particles by turbulence

Eaton, John K.; Fessler, John R.

doi:10.1016/0301-9322(94)90072-8

Cited by 761 publications

(455 citation statements)

References 63 publications

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“…In analogy to the WKB approximation in quantum mechanics (see, e.g. [32]), the authors construct perturbatively the steady solution to the Fokker-Planck equation associated to the reduced system (8) - (9). In the second part of this Section original results are reported where the particle dynamics is approximated as the advection by a synthetic flow comprising an effective compressible drift which accounts for leading-order corrections due to particle inertia.…”

Section: Small Stokes Number Asymptoticsmentioning

confidence: 99%

Stochastic suspensions of heavy particles

Bec

Cencini

Hillerbrand

et al. 2008

Physica D: Nonlinear Phenomena

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Turbulent suspensions of heavy particles in incompressible flows have gained much attention in recent years. A large amount of work focused on the impact that the inertia and the dissipative dynamics of the particles have on their dynamical and statistical properties. Substantial progress followed from the study of suspensions in model flows which, although much simpler, reproduce most of the important mechanisms observed in real turbulence. This paper presents recent developments made on the relative motion of a pair of particles suspended in time-uncorrelated and spatially self-similar Gaussian flows. This review is complemented by new results. By introducing a time-dependent Stokes number, it is demonstrated that inertial particle relative dispersion recovers asymptotically Richardson's diffusion associated to simple tracers. A perturbative (homogeneization) technique is used in the small-Stokes-number asymptotics and leads to interpreting first-order corrections to tracer dynamics in terms of an effective drift. This expansion implies that the correlation dimension deficit behaves linearly as a function of the Stokes number. The validity and the accuracy of this prediction is confirmed by numerical simulations.

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Section: Small Stokes Number Asymptoticsmentioning

confidence: 99%

Stochastic suspensions of heavy particles

Bec

Cencini

Hillerbrand

et al. 2008

Physica D: Nonlinear Phenomena

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“…It is largely accepted that particle transfer in the wall region and also deposition onto walls are processes dominated by near-wall turbulent coherent structures (sweeps and ejections), which are instantaneous realizations of the Reynolds stresses, and that particles tend to remain trapped along the streaks when in the viscous-layer [3][4][5]8,11 . However, the importance of these mechanisms for particle deposition depends on particle inertia.…”

Section: Introductionmentioning

confidence: 99%

Langevin PDF simulation of particle deposition in a turbulent pipe flow

Chibbaro

Minier

2008

Journal of Aerosol Science

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The paper deals with the description of particle deposition on walls from a turbulent flow over a large range of particle diameter, using a Langevin PDF model. The first aim of the work is to test how the present Langevin model is able to describe this phenomenon and to outline the physical aspects which play a major role in particle deposition. The general features and characteristics of the present stochastic model are first recalled. Then, results obtained with the standard form of the model are presented along with an analysis which has been carried out to check the sensitivity of the predictions on different mean fluid quantities. These results show that the physical representation of the near-wall physics has to be improved and that, in particular, one possible route is to introduce specific features related to the near-wall coherent structures. In the following, we propose a simple phenomenological model that introduces some of the effects due to the presence of turbulent coherent structures on particles in a thin layer close to the wall. The results obtained with this phenomenological model are in good agreement with ex-1 perimental evidence and this suggests to pursue in that direction, towards the development of more general and rigorous stochastic models that provide a link between a geometrical description of turbulent flow and a statistical one.

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“…Such particles possess inertia, and generally distribute in a strongly inhomogeneous manner. The common understanding of this long known but remarkable phenomenon of preferential concentrations relies on the idea that, in a turbulent flow, vortices act as centrifuges ejecting particles heavier than the fluid and entrapping lighter ones [4]. This picture was successfully used (see, e.g., [4,5]) to describe the small-scale particle distribution and to show that it depends only on the Stokes number S = , which is obtained by nondimensionalizing the particle response time with the characteristic time of the small turbulent eddies.…”

mentioning

confidence: 99%

Heavy Particle Concentration in Turbulence at Dissipative and Inertial Scales

Bec

Biferale

Cencini³

et al. 2007

Phys. Rev. Lett.

328

334

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Spatial distributions of heavy particles suspended in an incompressible isotropic and homogeneous turbulent flow are investigated by means of high resolution direct numerical simulations. In the dissipative range, it is shown that particles form fractal clusters with properties independent of the Reynolds number. Clustering is there optimal when the particle response time is of the order of the Kolmogorov time scale . In the inertial range, the particle distribution is no longer scale invariant. It is, however, shown that deviations from uniformity depend on a rescaled contraction rate, which is different from the local Stokes number given by dimensional analysis. Particle distribution is characterized by voids spanning all scales of the turbulent flow; their signature in the coarse-grained mass probability distribution is an algebraic behavior at small densities.

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Preferential concentration of particles by turbulence

Cited by 761 publications

References 63 publications

Stochastic suspensions of heavy particles

Stochastic suspensions of heavy particles

Langevin PDF simulation of particle deposition in a turbulent pipe flow

Heavy Particle Concentration in Turbulence at Dissipative and Inertial Scales

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