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Reexamination of string phase and shear thickening in simple fluids
Jerome Delhommelle1, J Petravic, Denis J Evans
1Equipe de Chimie et Biochimie Théoriques, UMR 7565, Université Henri Poincaré Nancy I, Boîte Postale 239, F-54506 Vandoeuvre-lès-Nancy, France.
Summary
The shear-induced string phase in hard sphere simulations is an artifact, not a real phenomenon. New methods reveal a shear-thickening behavior, aligning with experimental observations in colloidal dispersions.
Area of Science:
- * Physics
- * Physical Chemistry
- * Materials Science
Background:
- * Erpenbeck's 1984 simulations suggested shear-induced particle alignment into strings.
- * The validity of these findings was questioned due to thermostat-induced artifacts.
- * Previous research focused on refining velocity profile calculations.
Purpose of the Study:
- * To investigate the genuine nature of the shear-induced string phase.
- * To explore alternative methods for analyzing particle behavior under shear.
- * To resolve discrepancies between simulation and experimental results.
Main Methods:
- * Application of a novel configurational temperature expression.
- * Utilization of a configurational thermostat, independent of streaming velocity profiles.
- * Nonequilibrium molecular dynamics simulations of hard spheres.
Main Results:
- * The shear-induced string phase was identified as a simulation artifact.
- * A shear-thickening regime was observed.
- * Results align with experimental findings in concentrated colloidal dispersions.
Conclusions:
- * The configurational temperature approach provides a more accurate analysis of nonequilibrium systems.
- * Shear-induced string formation is not an intrinsic property of hard spheres under shear.
- * The study reconciles simulation predictions with experimental observations of shear-thickening.