Incollection,
Simulation study on microscopic structure and transport of phase interface
Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)
Abstract
Structure of the phase interaface has crucial importance in a phase separation,
and theoretical description of nucleation is one of the biggest challenge
that understand the heat conduction of the nonequilibrium steady state.
Although the study of this issue has long history,
the naive nucleation theory assuming a discontinuous density at the interface
does not give a good description of boiling water and theoretical description based
on microscopic dynamics is still unsatisfactory.
Theoretical studies using computer simulation have beed developed much
from the view point of molecular dynamics.
We study the structure of the gas-liquid interface of
the three-dimensional Lennard-Jones particle system.
Using nonequilibrium molecular dynamics,
heat flux maintains the system into a gas-liquid coexisting state and the system reaches a steady state.
In the steady state, there is a steady gas-liquid interface and
Fourier-type heat conduction is reproduced in the gas phase and liquid phase with different gradients. In our simulation, it is observed that the interface has an asymmetric structure.
This interface is well described by a free energy density model with an asymmetric double-well form1. When the system approaches to the steady state,
a gap of the temperature profile appears between each phase and
the gap value is relaxed to a definite value.
It is observed that the thermal resistance exists in the gas-liquid interface
in microscopic scale.
In recent years,
the idea of an application for the interface thermal resistance, themal dioder, was proposed2-4.
We study the interface thermal resistance and thermal diode effect
using the three-dimensional Lennard-Jones particle system.
The system consists of two-types of Lennard-Jones particles
with different mass and strength of interaction.
In a steady state, Fourier-type heat conduction is reproduced and
a gap of the temperature profile is observed between the solid phase and liquid phase.
This solid-liquid system exhibits the thermal diode effect.
If we interpret the system as a series circuit,
and neglect temperature dependence of thermal resistance of solid and liquid phases,
the thermal diode effect reduces to the property of interface thermal resistance.
The ratio of the heat flux estimated from the above simulation is well described by this interpretation.
References\\
1) F. Ogushi, S. Yukawa and N.Ito, J. Phys. Soc. Jpn. 75, 073001 (2006).\\
2) B. Li, L Wang, and G. Casati, Phys. Rev. Lett. 93, 184301 (2004).\\
3) B. Li, J.-H Lan, and L Wang, Phys. Rev. Lett. 95, 104302 (2005).\\
4) C. W. Chang, D. Okawa, A. Majundar, and Z. Zettl, Science, 314, 1121 (2006).
