Tunable Hydrodynamic Interfacial Instability by Controlling a Thermodynamic Parameter of Liquid-Liquid Phase...

Area of Science:

• Fluid dynamics
• Thermodynamics
• Materials science

Background:

• Liquid-liquid phase separation is crucial in various scientific fields.
• Understanding interfacial instability is key to controlling fluid behavior.

Purpose of the Study:

• To investigate the hydrodynamic interfacial instability during fluid displacement.
• To explore the role of thermodynamic parameters, specifically salt concentration, in controlling this instability.
• To develop a theoretical framework for predicting pattern transitions.

Main Methods:

• Utilizing a Hele-Shaw cell to study fluid displacement.
• Manipulating salt concentration to alter solution miscibility and interfacial patterns.
• Analyzing interfacial instability through thermodynamic flux and interface growth rates.

Main Results:

• Observed stable circular, fingering, and droplet patterns with decreasing salt concentration.
• Demonstrated that interfacial instability persists even under hydrodynamically stable conditions.
• Developed a quantitative theoretical framework to predict pattern transition points.

Conclusions:

• Salt concentration is a critical thermodynamic parameter for controlling hydrodynamic interfacial instability.
• The study provides a predictive model for pattern formation in Hele-Shaw cells.
• Observed pattern transitions are linked to increased entropy production, aligning with thermodynamic principles.