Work

Exact hydrodynamic manifolds for the linear Boltzmann BGK equation II: spectral closure

Year: 2025

Type: article

Abstract: We give an explicit description of the spectral closure for the three-dimensional linear Boltzmann-BGK equation in terms of the macroscopic fields, density, flow velocity and temperature. This results in a new linear fluid dynamics model which is valid for any relaxation time, thus providing an optimal hydrodynamic model for rarefied gas flow over a large range of Knudsen numbers. The non-local exact fluid dynamics equations are compared to the Euler, Navier–Stokes and Burnett equations. Our results are based on a detailed spectral analysis of the linearized Boltzmann-BGK operator together with a suitable choice of spectral projection.

Source: Continuum Mechanics and Thermodynamics

DOI: 10.1007/s00161-025-01379-8

Authors: Florian Kogelbauer, Ilya Karlin

Institution: ETH Zurich

Language: English

Topic: Gas Dynamics and Kinetic Theory

Subfield: Applied Mathematics

Field: Mathematics

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $2,990

Funder: Eidgenössische Technische Hochschule Zürich