Speed of sound in dense simple liquids

Fuente: arXiv
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Autore principale: Khrapak, Sergey
Natura: Preprint
Pubblicazione: 2025
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author Khrapak, Sergey
author_facet Khrapak, Sergey
contents The speed of sound of simple dense fluids is shown to exhibit a pronounced freezing temperature scaling of the form $c_{\rm s}/v_{\rm T}\simeq \sqrtγ +α(T_{\rm fr}/T)^β$, where $c_s$ is the speed of sound, $v_{\rm T}$ is the characteristic thermal velocity, $γ$ is the ideal gas heat capacity ratio, $T$ is the temperature, $T_{\rm fr}$ is the freezing temperature, and $α$ and $β$ are dimensionless parameters. For the Lennard-Jones fluid we get $γ=5/3$, $α\simeq 7$ with a weak temperature dependence, and $β= 1/3$. Similar scaling works in several real liquids, such as argon, krypton, xenon, nitrogen, and methane. In this case, $α$ and $β$ are substance-dependent fitting parameters. A comparison between the prediction of this freezing temperature scaling and a recent experimental measurement of the speed of sound in methane under conditions of planetary interiors is presented and discussed. The results provide a simple practical tool to estimate the speed of sound in regimes where no experimental data are yet available.
format Preprint
id arxiv_https___arxiv_org_abs_2507_16967
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Speed of sound in dense simple liquids
Khrapak, Sergey
Soft Condensed Matter
Statistical Mechanics
Chemical Physics
The speed of sound of simple dense fluids is shown to exhibit a pronounced freezing temperature scaling of the form $c_{\rm s}/v_{\rm T}\simeq \sqrtγ +α(T_{\rm fr}/T)^β$, where $c_s$ is the speed of sound, $v_{\rm T}$ is the characteristic thermal velocity, $γ$ is the ideal gas heat capacity ratio, $T$ is the temperature, $T_{\rm fr}$ is the freezing temperature, and $α$ and $β$ are dimensionless parameters. For the Lennard-Jones fluid we get $γ=5/3$, $α\simeq 7$ with a weak temperature dependence, and $β= 1/3$. Similar scaling works in several real liquids, such as argon, krypton, xenon, nitrogen, and methane. In this case, $α$ and $β$ are substance-dependent fitting parameters. A comparison between the prediction of this freezing temperature scaling and a recent experimental measurement of the speed of sound in methane under conditions of planetary interiors is presented and discussed. The results provide a simple practical tool to estimate the speed of sound in regimes where no experimental data are yet available.
title Speed of sound in dense simple liquids
topic Soft Condensed Matter
Statistical Mechanics
Chemical Physics
url https://arxiv.org/abs/2507.16967