Molecular dynamics simulation of phase separating binary liquids in cylindrical Couette flow.

Area of Science:

• Fluid dynamics
• Materials science
• Computational physics

Background:

• Phase separation is crucial in materials science.
• Understanding fluid behavior in confined geometries is essential for various applications.
• Taylor-Couette flow provides a unique system for studying shear effects on fluid mixtures.

Purpose of the Study:

• To investigate the phase separation of a fluid mixture in a confined, curved Taylor-Couette geometry.
• To analyze the impact of shear flow on the resulting structures.
• To identify the role of geometry and shear rate in phase separation dynamics.

Main Methods:

• Molecular dynamics simulations were employed.
• A 50:50 fluid mixture was studied in a Taylor-Couette cell.
• Simulations were performed under both nonsheared and sheared conditions.

Main Results:

• Nonsheared systems exhibited equilibrium stacked structures (flat or curved).
• Sheared systems showed stable prearranged stacks due to high free energy barriers.
• Curved walls induced interfacial waves, absent in flat geometries.
• Shear rate influenced stack orientation and led to complex patterns at higher rates.

Conclusions:

• Confined, curved geometries promote stacked phase separation structures.
• Shear flow can kinetically trap configurations and induce unique phenomena like interfacial waves.
• The transition to complex patterns is linked to the crossover from diffusive to viscous growth regimes.