Title: Evolution of the age-included nearest pair distribution in disperse multiphase flows

Abstract

The age of the nearest particle pair is introduced as the difference between the current time and the most recent time when the nearest particle pair was formed. The evolution equation for the age-included nearest pair distribution function is derived. With the assumption of random destruction of the nearest particle pairs, the evolution equation predicts the exponential probability distribution of the ages of the nearest particle pairs. Particle-resolved numerical simulations with moving particles are performed to verify this prediction. The equation is then used to derive the evolution equation for the particle–fluid–particle (PFP) stress, which is known to be related to hyperbolicity of the two-fluid equations. It is found that the relaxation time of the age probability distribution is also the relaxation time for the PFP stress. Guided by the closure terms in the PFP stress evolution equation, we study kinematics of the nearest particle pairs in the particle-resolved simulations for flows caused by sedimentation of the particles with initially isotropic and homogeneous particle distributions. At the steady states, the particle Reynolds numbers are around 20. Anisotropy and inhomogeneity of particle distributions are seen to develop in these flows. The mean distances to the nearest particles and evolution of themore » distribution of the Voronoi cell volumes are studied. We also found the PFP stress is closely related to the changes in these inter-particle scale quantities.« less

Authors:

Zhang, Duan Zhong  ^[1];

• Search DOE PAGES for author "Zhang, Duan Zhong"
• Search DOE PAGES for ORCID "0000-0002-5611-2250"

Wang, Min  ^[1];

• Search DOE PAGES for author "Wang, Min"
• Search DOE PAGES for ORCID "0000-0002-4454-2480"

Balachandar, S.  ^[2]

• Search DOE PAGES for author "Balachandar, S."
• Search DOE PAGES for ORCID "0000-0003-3619-3695"

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+ Show Author Affiliations

1. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
2. University of Florida, Gainesville, FL (United States)

Publication Date:

Fri Jun 02 00:00:00 EDT 2023

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); US Department of the Navy, Office of Naval Research (ONR); Multidisciplinary University Research Initiatives (MURI) Program

OSTI Identifier:

1990112

Report Number(s):

LA-UR-22-24017
Journal ID: ISSN 1070-6631; TRN: US2403972

Grant/Contract Number:  

89233218CNA000001; dena0002378; N00014-16-1-2617

Resource Type:

Accepted Manuscript

Journal Name:

Physics of Fluids

Additional Journal Information:

Journal Volume: 35; Journal Issue: 6; Journal ID: ISSN 1070-6631

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Probability theory; Voronoi diagrams; Multiphase flows; Fluid drag; Kinetic theory; Particle distributions; Particle statistics