Mass dependence of shear viscosity in a binary fluid mixture: mode-coupling theory

Area of Science:

• Physical Chemistry
• Fluid Dynamics
• Statistical Mechanics

Background:

• Understanding the shear viscosity of fluid mixtures is crucial for predicting their macroscopic behavior.
• Previous models often struggle to accurately capture the mass dependence in isotopic mixtures.

Purpose of the Study:

• To derive an accurate theoretical expression for shear viscosity in binary fluid mixtures.
• To investigate the influence of mass dependence on shear viscosity.
• To propose a novel relationship between diffusion and viscosity.

Main Methods:

• Utilized mode-coupling theory to formulate an expression for shear viscosity.
• Employed molecular dynamics simulations for binary isotopic Lennard-Jones fluid mixtures.
• Analyzed results across a wide range of mass ratios and compositions.

Main Results:

• The derived theoretical expression for shear viscosity shows excellent agreement with simulation data.
• The study successfully captures the mass dependence of shear viscosity in isotopic mixtures.
• A new generalized Stokes-Einstein relation was proposed, linking individual diffusivities to shear viscosity.

Conclusions:

• Mode-coupling theory provides a robust framework for predicting shear viscosity in binary fluid mixtures.
• The findings validate the theoretical model and offer insights into mass effects.
• The proposed generalized relation offers a new tool for analyzing transport properties in fluid mixtures.