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Universality, Scaling, and Collapse in Supercritical Fluids
Min Young Ha1, Tae Jun Yoon1, Tsvi Tlusty2,3
1School of Chemical and Biological Engineering, Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea.
The Journal of Physical Chemistry Letters
|December 28, 2019
Summary
Supercritical fluids (SCF) exhibit universal scaling laws, simplifying their complex behavior. Machine learning reveals SCFs are mixtures of two microstates, explaining their unique properties.
Area of Science:
- Thermodynamics
- Fluid Dynamics
- Statistical Mechanics
Background:
- Supercritical fluids (SCF) display complex thermodynamic and dynamic properties, including molecular inhomogeneity.
- The fundamental physics behind these anomalies in SCFs remains poorly understood.
Purpose of the Study:
- To uncover the underlying physics governing supercritical fluid behavior.
- To identify universal principles governing the properties of supercritical fluids.
Main Methods:
- Utilized machine learning to extract an order parameter representing the fraction of gas-like or liquid-like molecules.
- Analyzed isotherms and phase diagrams of various supercritical fluids.
Main Results:
- Discovered that all isotherms of a given fluid collapse onto a single master curve following a power-law scaling relation.
- Demonstrated that phase diagrams of different compounds also collapse onto master curves with a universal scaling exponent.
- Identified a putative law of corresponding supercritical states for simple fluids.
Conclusions:
- Supercritical fluids can be modeled as a mixture of two interchangeable microstates.
- The spatiotemporal dynamics of these microstates explain the unique macroscopic properties of SCFs.
- The findings reveal simplicity and universality in supercritical fluid behavior.
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