Detailed characterization of extreme clustering at near-contact scales in isotropic turbulence.
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| Title: | Detailed characterization of extreme clustering at near-contact scales in isotropic turbulence. |
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| Authors: | Johnson, Danielle R.1, Hammond, Adam L.1, Bragg, Andrew D.2 andrew.bragg@duke.edu, Hui Meng1 huimeng@buffalo.edu |
| Source: | Journal of Fluid Mechanics. 3/10/2024, Vol. 982, p1-29. 29p. |
| Subjects: | Turbulence, Radial distribution function, Clustering of particles, Relative velocity, Stokes flow |
| Abstract: | Recent measurements of inertial particles in isotropic turbulence (Hammond & Meng, J. Fluid Mech., vol. 921, 2021, A16) revealed surprising extreme clustering of particles at near-contact separations (r), whereby the radial distribution function, g(r), grows from O(10) to O(103) with a (r/a) -6 scaling (where a is the particle radius), and a surprising upturn of the mean inward particle-pair relative velocity (MIRV). Hydrodynamic interactions (HIs) were proposed to explain the extreme clustering, but despite predicting the correct scaling (r/a) -6, the HI theory underpredicted g(r) by at least two orders of magnitude (Bragg et al., J. Fluid Mech., vol. 933, 2022, A31). To further understand the extreme clustering phenomenon and the relevance of HI, we characterize g(r) and particle-pair kinematics for Stokes numbers 0.07 = St = 3.68 in a homogeneous isotropic turbulence chamber using three-dimensional (3-D) particle tracking resolved to near-contact. A drift-diffusion equation governing g(r) is presented to investigate the kinematic mechanisms of particle pairs. Measurements in all 24 conditions show that when r/a x 20, extreme clustering consistently occurs, scaling as g(r) ~ (r/a) -k with 4.5 = k = 7.6, which increases with St. Here g(r) varies with St, particle size, density and polydispersity in ways that HI cannot explain. The extreme clustering region features an inward drift contributed by particle-pair turbophoresis and an inward radial relative acceleration. The latter indicates an interparticle attractive force at these separations that HI also cannot explain. The MIRV turns upward when approaching the extreme clustering region, opposite to direct numerical simulation predictions. These observations further support our previous assessment that extreme clustering arises from particle-particle interactions, but HI is not the main mechanism. [ABSTRACT FROM AUTHOR] |
| Copyright of Journal of Fluid Mechanics is the property of Cambridge University Press and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 176134800 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Detailed characterization of extreme clustering at near-contact scales in isotropic turbulence. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Johnson%2C+Danielle+R%2E%22">Johnson, Danielle R.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Hammond%2C+Adam+L%2E%22">Hammond, Adam L.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Bragg%2C+Andrew+D%2E%22">Bragg, Andrew D.</searchLink><relatesTo>2</relatesTo><i> andrew.bragg@duke.edu</i><br /><searchLink fieldCode="AR" term="%22Hui+Meng%22">Hui Meng</searchLink><relatesTo>1</relatesTo><i> huimeng@buffalo.edu</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Journal+of+Fluid+Mechanics%22">Journal of Fluid Mechanics</searchLink>. 3/10/2024, Vol. 982, p1-29. 29p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Turbulence%22">Turbulence</searchLink><br /><searchLink fieldCode="DE" term="%22Radial+distribution+function%22">Radial distribution function</searchLink><br /><searchLink fieldCode="DE" term="%22Clustering+of+particles%22">Clustering of particles</searchLink><br /><searchLink fieldCode="DE" term="%22Relative+velocity%22">Relative velocity</searchLink><br /><searchLink fieldCode="DE" term="%22Stokes+flow%22">Stokes flow</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Recent measurements of inertial particles in isotropic turbulence (Hammond & Meng, J. Fluid Mech., vol. 921, 2021, A16) revealed surprising extreme clustering of particles at near-contact separations (r), whereby the radial distribution function, g(r), grows from O(10) to O(103) with a (r/a) -6 scaling (where a is the particle radius), and a surprising upturn of the mean inward particle-pair relative velocity (MIRV). Hydrodynamic interactions (HIs) were proposed to explain the extreme clustering, but despite predicting the correct scaling (r/a) -6, the HI theory underpredicted g(r) by at least two orders of magnitude (Bragg et al., J. Fluid Mech., vol. 933, 2022, A31). To further understand the extreme clustering phenomenon and the relevance of HI, we characterize g(r) and particle-pair kinematics for Stokes numbers 0.07 = St = 3.68 in a homogeneous isotropic turbulence chamber using three-dimensional (3-D) particle tracking resolved to near-contact. A drift-diffusion equation governing g(r) is presented to investigate the kinematic mechanisms of particle pairs. Measurements in all 24 conditions show that when r/a x 20, extreme clustering consistently occurs, scaling as g(r) ~ (r/a) -k with 4.5 = k = 7.6, which increases with St. Here g(r) varies with St, particle size, density and polydispersity in ways that HI cannot explain. The extreme clustering region features an inward drift contributed by particle-pair turbophoresis and an inward radial relative acceleration. The latter indicates an interparticle attractive force at these separations that HI also cannot explain. The MIRV turns upward when approaching the extreme clustering region, opposite to direct numerical simulation predictions. These observations further support our previous assessment that extreme clustering arises from particle-particle interactions, but HI is not the main mechanism. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Journal of Fluid Mechanics is the property of Cambridge University Press and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1017/jfm.2023.1059 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 29 StartPage: 1 Subjects: – SubjectFull: Turbulence Type: general – SubjectFull: Radial distribution function Type: general – SubjectFull: Clustering of particles Type: general – SubjectFull: Relative velocity Type: general – SubjectFull: Stokes flow Type: general Titles: – TitleFull: Detailed characterization of extreme clustering at near-contact scales in isotropic turbulence. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Johnson, Danielle R. – PersonEntity: Name: NameFull: Hammond, Adam L. – PersonEntity: Name: NameFull: Bragg, Andrew D. – PersonEntity: Name: NameFull: Hui Meng IsPartOfRelationships: – BibEntity: Dates: – D: 10 M: 03 Text: 3/10/2024 Type: published Y: 2024 Identifiers: – Type: issn-print Value: 00221120 Numbering: – Type: volume Value: 982 Titles: – TitleFull: Journal of Fluid Mechanics Type: main |
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