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An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Stationary temperature profiles in a liquid nanochannel: comparisons between molecular-dynamics simulation and
Hisashi Okumura1, David M Heyes
1Department of Physics, School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan. hokumura@tb.phys.nagoya-u.ac.jp
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|February 7, 2007
Summary
Molecular-dynamics (MD) simulations and hydrostatic solutions reveal differences in liquid behavior under temperature gradients. The study establishes the minimum length scale for hydrostatic solutions to accurately model these systems.
Area of Science:
- Computational Physics
- Thermodynamics
- Fluid Dynamics
Background:
- Investigating non-equilibrium states in liquids is crucial for understanding heat transfer and material properties.
- Hydrostatic (HS) solutions offer a simplified approach to modeling fluid behavior, but their applicability under varying conditions needs validation.
- Molecular-dynamics (MD) simulations provide a detailed, atomistic perspective on fluid behavior, serving as a benchmark for theoretical models.
Purpose of the Study:
- To compare the accuracy of molecular-dynamics (MD) simulations and hydrostatic (HS) solutions for Lennard-Jones liquids under temperature gradients.
- To determine the conditions and limitations of the HS approach in modeling non-equilibrium liquid systems.
- To analyze differences in thermodynamic properties, such as density and temperature, predicted by MD simulations and HS solutions.
Main Methods:
- Three-dimensional molecular-dynamics (MD) simulations were performed on a Lennard-Jones liquid system.
- A hydrostatic (HS) solution was used for comparison, modeling a liquid channel with varying temperature gradients.
- Analysis focused on pressure, density, potential energy, kinetic temperature, and configurational temperature profiles.
Main Results:
- Both MD simulations and HS solutions yielded flat normal pressure profiles in stationary non-equilibrium states.
- MD simulations showed oscillating density profiles near the boundary with infinite temperature gradients, unlike the stepwise HS profiles.
- Anomalies in potential energy were observed in MD simulations near the boundary; the HS approach was found to break down beyond a certain length scale.
Conclusions:
- The study establishes a minimum length scale for the validity of the hydrostatic solution approach in modeling temperature gradients.
- Significant differences exist between MD-derived and HS-derived density and potential energy profiles, particularly near temperature boundaries.
- Kinetic and configurational temperatures can diverge in the transition zone, highlighting the complexity of non-equilibrium thermodynamics.
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