Experimental Study on Double Emulsion Breakup Characteristics at a Microfluidic Y-Junction.

Area of Science:

• Fluid dynamics
• Microfluidics
• Colloid science

Background:

• Understanding droplet behavior in microfluidic devices is crucial for various applications.
• Double emulsions present complex dynamics due to multiple interfaces.

Purpose of the Study:

• To experimentally investigate the dynamic mechanisms of double emulsions in a microfluidic Y-junction.
• To categorize flow patterns and establish transition rules based on interfacial characteristics and influencing parameters.

Main Methods:

• Experimental study of double emulsion transport through a microfluidic Y-junction.
• Analysis of interfacial parameter evolution and breakup time.
• Development of flow pattern maps based on droplet lengths.

Main Results:

• Identified typical flow patterns and categorized them based on interfacial characteristics.
• Established transition rules influenced by droplet lengths and capillary number, noting more parameters for double emulsions than single emulsions.
• Discovered coupling interaction between interfaces affecting breakup threshold and developed flow pattern maps to delineate its occurrence domain.
• Derived expressions for breakup time and a relation for the transition line, which effectively separates regimes with and without coupling interaction across tested capillary numbers.

Conclusions:

• The study provides a comprehensive understanding of double emulsion dynamics in microfluidic Y-junctions.
• Developed relations offer a general method to predict and explain the transition lines based on droplet lengths and capillary number.
• Findings contribute to the design and optimization of microfluidic systems involving complex emulsions.