Long-time behavior and different shear regimes in quenched binary mixtures.

Area of Science:

• Soft Matter Physics
• Rheology
• Materials Science

Background:

• Diffusive binary systems exhibit complex morphological and rheological properties.
• Understanding these properties under external forces like shear is crucial for material design.
• Previous studies have explored shear effects, but a comprehensive understanding of late-time behavior is still developing.

Purpose of the Study:

• To investigate the dependence of morphological and rheological properties on applied shear in diffusive binary systems.
• To analyze the late-time behavior of domain size (Ly) and excess viscosity (Delta eta)M.
• To identify distinct shear regimes and their impact on system evolution.

Main Methods:

• Numerical simulations of diffusive binary systems quenched into the coexistence region.
• Application of controlled shear rates to observe system response.
• Analysis of domain transversal size (Ly) and maximum excess viscosity (Delta eta)M.

Main Results:

• Two distinct shear regimes (weak and strong) were identified, separated by a critical shear rate (gamma c).
• Domain size (Ly) and excess viscosity (Delta eta)M exhibit power-law dependencies on shear rate in both regimes.
• Specific exponents were determined for weak (alpha_w=0.25±0.01, nu_w=-0.68±0.04) and strong (alpha_s=0.18±0.02, nu_s=-2.00±0.01) shear regimes.
• Unlike systems with fluctuating velocity fields, domains were observed to grow continuously.

Conclusions:

• Applied shear significantly alters the morphological and rheological properties of diffusive binary systems.
• The identified shear regimes and their associated power-law behaviors provide quantitative insights into system dynamics.
• Continuous domain growth under shear, even at late times, distinguishes these systems from others with fluctuating velocity fields.