Slow heat-driven flow in a gas of hard disks
Abstract
We study a slow heat-driven flow in a gas of elastically colliding hard disks confined to a long channel. The initial state consists of two regions with large temperature and density contrasts but nearly equal pressures, leading to a low-Mach-number, nearly isobaric evolution. In the dilute limit, the corresponding isobaric hydrodynamic theory reduces to a previously known ideal-gas description. We extend this theory to finite densities by incorporating a non-ideal equation of state of a hard-disk fluid, and solve the resulting one-dimensional equations numerically. Finite-density effects produce appreciable deviations from the ideal-gas prediction. We then test the theory directly against event-driven molecular dynamics simulations of hard disks and find very good agreement in both the dilute and finite-density regimes. The results provide, to our knowledge, the first particle-level test of isobaric gas dynamics of a strongly inhomogeneous cooling flow.
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BibTeX
@misc{kumar2026slow,
title = {{Slow heat-driven flow in a gas of hard disks}},
author = {Amit Kumar and Abhishek Dhar and Baruch Meerson},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2607.00449},
eprint = {2607.00449},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.00449},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Slow heat-driven flow in a gas of hard disks
AU - Amit Kumar
AU - Abhishek Dhar
AU - Baruch Meerson
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2607.00449
UR - https://arxiv.org/abs/2607.00449
AB - We study a slow heat-driven flow in a gas of elastically colliding hard disks confined to a long channel. The initial state consists of two regions with large temperature and density contrasts but nearly equal pressures, leading to a low-Mach-number, nearly isobaric evolution. In the dilute limit, the corresponding isobaric hydrodynamic theory reduces to a previously known ideal-gas description. We extend this theory to finite densities by incorporating a non-ideal equation of state of a hard-disk fluid, and solve the resulting one-dimensional equations numerically. Finite-density effects produce appreciable deviations from the ideal-gas prediction. We then test the theory directly against event-driven molecular dynamics simulations of hard disks and find very good agreement in both the dilute and finite-density regimes. The results provide, to our knowledge, the first particle-level test of isobaric gas dynamics of a strongly inhomogeneous cooling flow.
ER -