Atomic Mechanism of Flow in Simple Liquids under Shear

TL;DR

This study uses molecular dynamics simulations to explore atomic correlations and local strain in simple liquids under shear, revealing how atomic topology changes relate to flow failure.

Contribution

It introduces a method to measure atomic-level strain via anisotropic pair-density functions and links local topology changes to flow failure.

Findings

Atomic correlations have limited spatial extent dependent on strain rate.

Local atomic strain extrapolates to zero at a critical strain rate.

Flow failure involves bond exchange altering atomic connectivity.

Abstract

Atomic correlations in a simple liquid in steady-state flow under shear stress were studied by molecular dynamics simulation. The local atomic level strain was determined through the anisotropic pair-density function (PDF). The atomic level strain has a limited spatial extension whose range is dependent on the strain rate and extrapolates to zero at the critical strain rate. A failure event is identified with altering the local topology of atomic connectivity by exchanging bonds among neighboring atoms.