Equilibrium and nonequilibrium dynamics of soft sphere fluids
1Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA. jeetain@lehigh.edu.
Soft Matter
|June 9, 2015
Summary
Computer simulations reveal that freezing-point scaling effectively relates transport properties like diffusivity and viscosity to thermodynamic parameters in soft sphere fluids. Particle softness significantly influences these relationships and structural changes under shear.
Area of Science:
- Computational physics
- Soft matter physics
- Statistical mechanics
Background:
- Transport coefficients (self-diffusivity, viscosity) are crucial for understanding fluid behavior.
- Particle softness, modified by inverse-power potential exponents, impacts thermodynamic and dynamic properties.
- Scaling relationships offer a way to unify diverse fluid system behaviors.
Purpose of the Study:
- To investigate the freezing-point scaling relationship for transport coefficients in soft sphere fluids.
- To explore the role of particle softness in equilibrium and nonequilibrium properties.
- To connect rheological behavior with underlying structural changes.
Main Methods:
- Computer simulations of inverse-power potential (IPP) fluids.
- Analysis of equilibrium transport coefficients (diffusivity, viscosity).
- Nonequilibrium molecular dynamics simulations for shear-dependent viscosity.
Main Results:
- Rescaled coupling parameter approximately collapses diffusivity and viscosity data for varying particle softness.
- Two-body excess entropy scaling provides near-perfect data collapse below the freezing transition.
- Softer particles exhibit stronger shear-thinning, linked to structural changes (order loss).
Conclusions:
- Freezing-point scaling is a useful, though imperfect, tool for comparing soft sphere fluid dynamics.
- Particle softness critically influences equilibrium and nonequilibrium transport properties.
- Shear-thinning mechanisms differ based on particle softness, affecting fluid structure.
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