Generalized flux-weighted boundary walls in kinetic models

Fuente: arXiv
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Main Authors: Barbieri, Luca, Di Cintio, Pierfrancesco
Format: Preprint
Published: 2026
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author Barbieri, Luca
Di Cintio, Pierfrancesco
author_facet Barbieri, Luca
Di Cintio, Pierfrancesco
contents We present a technique to investigate the stationary states of a system of a collisionless system confined by an external potential and coupled to boundary reservoirs through prescribed reinjection rules. We consider a family of boundary conditions parametrized by an integer $n$, corresponding to different velocity distributions imposed at the boundaries, generalizing the standard flux-weighted Maxwellian scheme. By combining Liouville's theorem with the boundary injection rule, we derive an explicit analytical expression for the stationary distribution function. This framework provides a direct link between microscopic boundary dynamics and macroscopic stationary profiles. We show that thermal equilibrium is recovered only for the standard flux-weighted injection method, while for all other cases the system relaxes to manifestly non-thermal stationary states. The resulting density and temperature profiles exhibit non-trivial spatial structures, including non-monotonic behaviour and temperature gradients induced by the boundary conditions alone. Analytical predictions for stationary moments are obtained in closed form for representative cases and are nicely reproduced by particle-based numerical simulations.
format Preprint
id arxiv_https___arxiv_org_abs_2604_24592
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Generalized flux-weighted boundary walls in kinetic models
Barbieri, Luca
Di Cintio, Pierfrancesco
Statistical Mechanics
Computational Physics
Plasma Physics
We present a technique to investigate the stationary states of a system of a collisionless system confined by an external potential and coupled to boundary reservoirs through prescribed reinjection rules. We consider a family of boundary conditions parametrized by an integer $n$, corresponding to different velocity distributions imposed at the boundaries, generalizing the standard flux-weighted Maxwellian scheme. By combining Liouville's theorem with the boundary injection rule, we derive an explicit analytical expression for the stationary distribution function. This framework provides a direct link between microscopic boundary dynamics and macroscopic stationary profiles. We show that thermal equilibrium is recovered only for the standard flux-weighted injection method, while for all other cases the system relaxes to manifestly non-thermal stationary states. The resulting density and temperature profiles exhibit non-trivial spatial structures, including non-monotonic behaviour and temperature gradients induced by the boundary conditions alone. Analytical predictions for stationary moments are obtained in closed form for representative cases and are nicely reproduced by particle-based numerical simulations.
title Generalized flux-weighted boundary walls in kinetic models
topic Statistical Mechanics
Computational Physics
Plasma Physics
url https://arxiv.org/abs/2604.24592