Kinetics of vapor-liquid and vapor-solid phase separation under gravity

Area of Science:

• Thermodynamics and Statistical Mechanics
• Computational Physics

Background:

• Phase separation is crucial in materials science and fluid dynamics.
• Understanding domain growth kinetics is key to controlling material properties.
• Anisotropic effects due to external fields are not fully understood.

Purpose of the Study:

• To investigate the influence of an external gravitational field on phase separation kinetics.
• To analyze the resulting domain morphology and scaling laws.
• To determine the impact of gravity on statistical self-similarity and the Porod law.

Main Methods:

• Extensive molecular dynamics simulations of a three-dimensional one-component Lennard-Jones system.
• Quenching a homogeneous system near critical density into the coexistence region.
• Analysis of domain growth in the presence and absence of an external gravitational field.

Main Results:

• Formation of bicontinuous domain structures upon quenching.
• Gravity destroys system isotropy, leading to anisotropic domain growth.
• Accelerated domain growth along the field direction, resembling sedimentation.
• Emergence of new length scales dependent on gravitational field strength.
• Modified scaling laws and verification of statistical self-similarity and Porod law in anisotropic systems.

Conclusions:

• External gravitational fields significantly alter phase separation kinetics and domain morphology.
• The study provides insights into anisotropic growth phenomena and their underlying mechanisms.
• Findings are relevant for understanding and manipulating phase transitions in various physical systems.