Possible oriented transition of multiple-emulsion globules with asymmetric internal structures in a microfluidic...

Area of Science:

• Fluid dynamics
• Microfluidics
• Rheology

Background:

• Symmetric globules show single transition patterns in constrictions.
• Asymmetric globules present multiple transition pathways and pressure drops based on internal droplet orientation.

Purpose of the Study:

• Investigate the oriented transition of a globule with two unequal inner droplets in an axisymmetric microfluidic constriction.
• Analyze the influence of initial droplet orientation on pressure drop and transition patterns.

Main Methods:

• Utilized a recently developed boundary integral method for numerical investigation.
• Simulated transitions driven by axisymmetric Poiseuille flow at a fixed volume flow rate.
• Carefully observed the rheological behaviors of the globule during transition.

Main Results:

• Observed multiple transition patterns for asymmetric globules.
• Found that the maximum pressure drop is lower when the larger inner droplet is initially at the front.
• Identified a potential tropism where globules pass more easily with the larger droplet leading.

Conclusions:

• The initial orientation of inner droplets significantly affects globule transition in constrictions.
• A tropism, possibly driven by pressure drops, may guide globules through constrictions with their larger internal droplet positioned forward.
• The study provides physical explanations for these observed phenomena.