A pragmatical access to the viscous flow

TL;DR

This paper develops a practical model relating the viscosity of undercooled liquids to Eshelby relaxations with finite lifetimes, based on shear relaxation data, revealing the relaxation mechanisms of internal stresses.

Contribution

It introduces a pragmatic approach to connect viscosity with Eshelby relaxations considering finite lifetimes, providing new insights into stress relaxation processes.

Findings

Less than half of internal stresses relax via single Eshelby relaxations

Majority of stresses dissolve at the terminal lifetime due to collective effects

Derived relation aligns with shear relaxation data

Abstract

The paper derives a relation for the viscosity of undercooled liquids on the basis of the pragmatical model concept of Eshelby relaxations with a finite lifetime. From accurate shear relaxation data in the literature, one finds that slightly less than half of the internal stresses relax directly via single Eshelby relaxations; the larger part dissolves at the terminal lifetime, which is a combined effect of many Eshelby relaxations.