Dynamics of a Deformable Compound Bubble within a Microchannel

Area of Science:

• Fluid dynamics
• Microfluidics
• Computational modeling

Background:

• Microfluidics enables synthesis of uniform compound bubbles for diagnostics, therapeutics, and material science.
• Compound bubbles offer precise control over core size, shell thickness, and core number.

Purpose of the Study:

• To numerically analyze the dynamics of deformable compound bubbles in microchannels.
• To investigate the effects of steady, oscillatory, and pulsatile flow conditions.
• To explore the behavior of dual and triple-core compound bubbles.

Main Methods:

• Utilized an in-house solver based on the Level Set method.
• Modeled a three-phase system for compound bubble dynamics.
• Analyzed flow conditions including steady Poiseuille, oscillatory, and pulsatile flows.

Main Results:

• Low Strouhal numbers caused significant bubble deformation and enhanced mixing, reducing residence time.
• High Strouhal numbers resulted in plug-like flow with minimal deformation and mixing.
• Multi-core bubble dynamics showed cores migrating to the leading edge or becoming trapped at the rear.
• Outer shell presence mitigated core property effects, leading to similar bubble and droplet dynamics.

Conclusions:

• Compound bubble dynamics are highly dependent on flow conditions (Strouhal number).
• Core positioning significantly influences their final location within the shell.
• Compound systems exhibit similar behavior to droplets, simplifying modeling under certain conditions.