# Solidification of the Lennard-Jones fluid near the wall in thermohydrodynamic lubrication

## TL;DR

This study uses molecular dynamics simulations to reveal that viscous heating can induce solidification of Lennard-Jones fluids near walls in thermohydrodynamic lubrication, highlighting a counterintuitive phase transition.

## Contribution

It uncovers the phenomenon of viscous heating-induced solidification of LJ fluids near walls and analyzes its microscopic and macroscopic mechanisms.

## Key findings

- Solidification occurs only with sufficient viscous heating.
- LJ molecules densely confine near the wall and solidify upon interaction with crystallized wall molecules.
- Band formation appears in highly confined regimes.

## Abstract

We investigate the thermohydrodynamic lubrication of the Lennard-Jones (LJ) fluid in the parallel-plate channel composed of the LJ particles by using molecular dynamics (MD) simulation. We discover a counterintuitive solidification of the LJ fluid near the wall, i.e., \textit{viscous heating-induced solidification}, where solidification occurs only when the viscous heating of the LJ fluid is sufficiently large. The solidification mechanism is investigated from both macroscopic and microscopic points of view. It is found that the LJ molecules are densely confined in the vicinity of the wall via the thermohydrodynamic transport of the bulk fluid and that when the local density in the vicinity of the wall is close to the solidification line in the phase diagram, the LJ molecules are solidified due to the interaction with the crystallized wall molecules. Band formation is also observed in the highly confined regime when the channel width is sufficiently large.