A spectral approach to interface layers on networks for the linearized BGK equation and its acoustic limit

Fuente: arXiv
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Autores principales: Borsche, Raul, Damm, Tobias, Klar, Axel, Zhou, Yizhou
Formato: Preprint
Publicado: 2026
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author Borsche, Raul
Damm, Tobias
Klar, Axel
Zhou, Yizhou
author_facet Borsche, Raul
Damm, Tobias
Klar, Axel
Zhou, Yizhou
contents We consider in this paper a velocity discretized version of the full linear kinetic BGK model and the corresponding limit for small Knudsen number, the linearised Euler or acoustic system. Considering these equations on networks, coupling conditions for the macroscopic equations are derived from the kinetic conditions via an asymptotic analysis near the nodes of the network. Here, a degeneracy in the limit equations requires not only the investigation of kinetic layers, but also the discussion of viscous layers. Using the kinetic coupling conditions at the junction and coupling kinetic and viscous layers to the outer problems on the edges one obtains a coupled kinetic half-space problem at each node. A spectral method is developed to solve this coupled kinetic half-space problems. This allows to obtain a detailed picture of the various interface layers near the nodes and to determine the relevant coefficients in the kinetic derived coupling conditions for the macroscopic equations.Numerical results show the accuracy and efficiency of the approach.
format Preprint
id arxiv_https___arxiv_org_abs_2603_06104
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A spectral approach to interface layers on networks for the linearized BGK equation and its acoustic limit
Borsche, Raul
Damm, Tobias
Klar, Axel
Zhou, Yizhou
Analysis of PDEs
Numerical Analysis
We consider in this paper a velocity discretized version of the full linear kinetic BGK model and the corresponding limit for small Knudsen number, the linearised Euler or acoustic system. Considering these equations on networks, coupling conditions for the macroscopic equations are derived from the kinetic conditions via an asymptotic analysis near the nodes of the network. Here, a degeneracy in the limit equations requires not only the investigation of kinetic layers, but also the discussion of viscous layers. Using the kinetic coupling conditions at the junction and coupling kinetic and viscous layers to the outer problems on the edges one obtains a coupled kinetic half-space problem at each node. A spectral method is developed to solve this coupled kinetic half-space problems. This allows to obtain a detailed picture of the various interface layers near the nodes and to determine the relevant coefficients in the kinetic derived coupling conditions for the macroscopic equations.Numerical results show the accuracy and efficiency of the approach.
title A spectral approach to interface layers on networks for the linearized BGK equation and its acoustic limit
topic Analysis of PDEs
Numerical Analysis
url https://arxiv.org/abs/2603.06104