Emulsion droplet formation in coflowing liquid streams

Area of Science:

• Fluid dynamics
• Microfluidics
• Emulsion science

Background:

• Emulsion formation is crucial in various industries.
• Understanding droplet breakup dynamics is key to controlling emulsion properties.
• Microfluidic devices offer precise control over fluid interfaces.

Purpose of the Study:

• To investigate droplet formation in coflowing liquid streams.
• To analyze the dynamics of dripping and jetting regimes using computational fluid dynamics.
• To determine the optimal regime for producing monodisperse emulsions.

Main Methods:

• Computational fluid dynamics (CFD) simulations.
• Volume-of-fluid (VOF) method for interface tracking.
• Analysis of experimental observations in coflowing microchannels.

Main Results:

• Simulations successfully reproduced dripping, widening jetting, and narrowing jetting regimes.
• The dripping regime was identified as favorable for producing monodisperse emulsions.
• Droplet breakup mechanisms differ between dripping/widening jetting (pressure-driven) and narrowing jetting (velocity-driven).
• Capillary and Weber numbers influence drop diameter, generation rate, and emulsification regime.

Conclusions:

• The dripping regime is preferred for generating monodisperse emulsions.
• Pressure and velocity dynamics dictate droplet breakup in different regimes.
• Fluid properties (capillary and Weber numbers) are critical parameters for controlling emulsification.