Molecular transport through a bottleneck driven by external force

TL;DR

This study uses molecular dynamics simulations to analyze how Lennard-Jones molecules pass through a bottleneck under external force, revealing two flow regimes separated by a critical force and highlighting the influence of temperature.

Contribution

It identifies a critical external force and flow rate relationship, and elucidates the temperature dependence of molecular transport through a bottleneck, which is a novel insight.

Findings

Two distinct flow regimes separated by a critical force

Flow rate scales with external force and geometry

Temperature affects molecular flow behavior

Abstract

The transport phenomena of Lennard-Jones molecules through a structural bottleneck driven by an external force are investigated by molecular dynamics simulations. We observe two distinct molecular flow regimes distinguished by a critical external force $F_{c}$ and find scaling behaviors between external forces and flow rates. Below the threshold $F_{c}$, molecules are essentially stuck in the bottleneck due to the attractive interaction between the molecules, while above $F_{c}$, molecules can smoothly move in the pipe. A critical flow rate $q_{c}$ corresponding to $F_{c}$ satisfies a simple relationship with angles and the value of $q_{c}$ can be estimated by a simple argument. We further clarify the role of the temperature dependence in the molecular flows through the bottleneck.