Slow heat-driven flow in a gas of hard disks

Amit Kumar; Abhishek Dhar; Baruch Meerson

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arXiv · 2607.00449

Slow heat-driven flow in a gas of hard disks

Amit Kumar·Abhishek Dhar·Baruch Meerson

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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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Amit Kumar, Abhishek Dhar, Baruch Meerson. 2026-07-01. Slow heat-driven flow in a gas of hard disks. https://arxiv.org/abs/2607.00449

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