The effect of emulsifier concentration on turbulent drop breakup - An experimental study based on single drop...

Area of Science:

• Fluid Dynamics
• Colloid and Surface Science

Background:

• Classic studies on emulsifier effects in turbulent drop breakup often use slow/laminar techniques.
• Quasi-steady state interfacial tension measurements may not fully capture dynamic emulsifier behavior.

Purpose of the Study:

• To investigate the influence of polysorbate 20 concentration on turbulent drop deformation and breakup.
• To develop a modified Weber number for characterizing emulsifier effects under turbulent stress.

Main Methods:

• Utilized single drop breakup visualizations to observe the effects of polysorbate 20.
• Compared experimental results with quiescent drop tensiometry and emulsification experiments.

Main Results:

• High emulsifier concentrations increased breakup probability and rate, while decreasing breakup timescales.
• Observed a significant reduction in effective interfacial tension under turbulent conditions, less than predicted by static tensiometry.
• Identified elastic resistance at intermediate concentrations, suggesting complex adsorption dynamics.

Conclusions:

• A modified Weber number effectively captures emulsifier and stress effects in turbulent drop breakup.
• Turbulent conditions are crucial for understanding emulsifier behavior, as static methods are insufficient.
• Emulsifier adsorption during emulsification is not solely diffusion-limited and exhibits elastic properties.