Kinetic closure of turbulence

Fuente: arXiv
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Auteurs principaux: Marson, Francesco, Malaspinas, Orestis
Format: Preprint
Publié: 2025
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author Marson, Francesco
Malaspinas, Orestis
author_facet Marson, Francesco
Malaspinas, Orestis
contents This letter presents a kinetic closure of the filtered Boltzmann--BGK equation, paving the way toward an alternative description of turbulence. The closure retains the turbulent subfilter stress tensor without a separate Smagorinsky-type ansatz for its structure, unlike classical filtered Navier--Stokes closures. In contrast, it accounts for the subfilter turbulent diffusion in the nonconserved moments by generalizing the BGK collision operator. The model does not require scale separation between resolved and unresolved scales. The Chapman--Enskog analysis shows how its hydrodynamic limit can converge to the filtered Navier--Stokes equations, with velocity gradients isolating subfilter contributions. Numerical tests on the Taylor--Green vortex and the turbulent mixing layer show improved stability and reduced dissipation in the reported cases, benchmarked against the Smagorinsky model.
format Preprint
id arxiv_https___arxiv_org_abs_2510_00779
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Kinetic closure of turbulence
Marson, Francesco
Malaspinas, Orestis
Fluid Dynamics
Computational Physics
This letter presents a kinetic closure of the filtered Boltzmann--BGK equation, paving the way toward an alternative description of turbulence. The closure retains the turbulent subfilter stress tensor without a separate Smagorinsky-type ansatz for its structure, unlike classical filtered Navier--Stokes closures. In contrast, it accounts for the subfilter turbulent diffusion in the nonconserved moments by generalizing the BGK collision operator. The model does not require scale separation between resolved and unresolved scales. The Chapman--Enskog analysis shows how its hydrodynamic limit can converge to the filtered Navier--Stokes equations, with velocity gradients isolating subfilter contributions. Numerical tests on the Taylor--Green vortex and the turbulent mixing layer show improved stability and reduced dissipation in the reported cases, benchmarked against the Smagorinsky model.
title Kinetic closure of turbulence
topic Fluid Dynamics
Computational Physics
url https://arxiv.org/abs/2510.00779