Thermal fluctuations in metastable fluids

What is it about?

In this work, I discuss some theoretical and numerical results on thermal fluctuations statistics in metastable fluids. By modeling the fluid with the mesoscale Van der Walls squared-gradient theory (SGT) I found that the statistics of the fluctuations in metastable states strongly differ from the stable ones and they are not well described by classical fluctuations theories of simple fluids. Specifically, the discrepancy with the classical theory is exacerbated by increasing the metastability degree of the considered fluid. Peculiarly, when the fluid approaches spinodal loci, the classical theory seems to provide a divergent behavior of the intensity of the fluctuations, while the SGT expectations are convergent. Analytical expressions of the correlation function are obtained, and by averaging them over coarse-grained volumes unexpected scaling laws with the volumes of the coarse-graining cell are found. It is also proved that under some assumptions the SGT converges to the classical one. Fluctuating Hydrodynamics Equations are numerically solved to corroborate the theoretical findings.

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Why is it important?

Metastable fluids are a subject of longstanding interest that received considerable attention in fluid mechanics, physics of fluid, and soft matter communities over the years. Under this respect, the present results could be of interest to nucleation theories in metastable fluids, and more in general in thermally activated phase transitions.