2025/07/22 by Khrapak, Sergey · 2 citations
#Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Soft Condensed Matter (cond-mat.soft) #Statistical Mechanics (cond-mat.stat-mech)
paper · doi:10.48550/arxiv.2507.16967
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≃ √γ +α(T\rm fr/T)β, where cs 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≃ 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.