Fisher entropic Fokker-Planck model of monatomic rarefied gases

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Main Authors: Montanaro, Veronica, Netterdon, Lukas, Torrilhon, Manuel, Gorji, Hossein
Format: Preprint
Published: 2025
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author Montanaro, Veronica
Netterdon, Lukas
Torrilhon, Manuel
Gorji, Hossein
author_facet Montanaro, Veronica
Netterdon, Lukas
Torrilhon, Manuel
Gorji, Hossein
contents Particle-based stochastic approximations of the Boltzmann equation are popular tools for simulations of non-equilibrium gas flows, for which the Navier-Stokes-Fourier equations fail to provide accurate description. However, these numerical methods are computationally demanding, especially in the near-continuum regime, where the collisions become overwhelming. On the other hand, the Fokker-Planck kinetic models offer an efficient alternative, as the binary collisions are described by a diffusive process. Despite the intuitive advantage, rigorous and efficient Fokker-Planck approximations of the Boltzmann equation remain an open problem. On one hand, the moment projection of the Fokker-Planck operator should be consistent with that of the Boltzmann operator. On the other hand, the Fokker-Planck model should be constructed in such a way that the H-theorem is satisfied. The central aim of this study is fulfilling these two categorically different constraints, i.e. moment matching and entropy dissipation, within a flexible and tractable Fokker-Planck framework. To this end, we introduce a Fisher information-based entropic constraint and demonstrate that, with a suitable polynomial expansion of the drift term, it is possible to simultaneously achieve weak moment matching while honouring the H-theorem. We support our theoretical result by numerical experiments on the shock problem, validating our Fisher Entropic Fokker-Planck framework.
format Preprint
id arxiv_https___arxiv_org_abs_2509_06610
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Fisher entropic Fokker-Planck model of monatomic rarefied gases
Montanaro, Veronica
Netterdon, Lukas
Torrilhon, Manuel
Gorji, Hossein
Numerical Analysis
82C40, 60J60, 65C20
Particle-based stochastic approximations of the Boltzmann equation are popular tools for simulations of non-equilibrium gas flows, for which the Navier-Stokes-Fourier equations fail to provide accurate description. However, these numerical methods are computationally demanding, especially in the near-continuum regime, where the collisions become overwhelming. On the other hand, the Fokker-Planck kinetic models offer an efficient alternative, as the binary collisions are described by a diffusive process. Despite the intuitive advantage, rigorous and efficient Fokker-Planck approximations of the Boltzmann equation remain an open problem. On one hand, the moment projection of the Fokker-Planck operator should be consistent with that of the Boltzmann operator. On the other hand, the Fokker-Planck model should be constructed in such a way that the H-theorem is satisfied. The central aim of this study is fulfilling these two categorically different constraints, i.e. moment matching and entropy dissipation, within a flexible and tractable Fokker-Planck framework. To this end, we introduce a Fisher information-based entropic constraint and demonstrate that, with a suitable polynomial expansion of the drift term, it is possible to simultaneously achieve weak moment matching while honouring the H-theorem. We support our theoretical result by numerical experiments on the shock problem, validating our Fisher Entropic Fokker-Planck framework.
title Fisher entropic Fokker-Planck model of monatomic rarefied gases
topic Numerical Analysis
82C40, 60J60, 65C20
url https://arxiv.org/abs/2509.06610