Flow-driven competition between two capsules passing through a narrow pore

Area of Science:

• Fluid Dynamics
• Computational Mechanics
• Biophysics

Background:

• Understanding capsule behavior in confined flows is crucial for microfluidics and biomedical applications.
• Simulating deformable objects in narrow constrictions presents significant computational challenges.

Purpose of the Study:

• To investigate the flow-driven competition and passage order of two soft capsules through a narrow pore.
• To analyze the influence of capsule size, flow conditions, and initial positions on capsule dynamics.

Main Methods:

• Finite element simulation incorporating a distance function.
• Arbitrary Lagrangian-Eulerian (ALE) formulation for fluid-structure interaction.
• Analysis of capsule motion, deformation, and flow field changes.

Main Results:

• The larger capsule typically exhibits a stronger tendency to pass through the pore first, attributed to higher resistance and volume advantage.
• The passage order can be reversed by altering inlet velocity and initial capsule positioning.
• Distinct flow field alterations occur as capsules approach and navigate the pore.

Conclusions:

• Capsule size is a key factor in determining passage order, but it is not the sole determinant.
• Flow parameters and initial conditions offer avenues to control the dynamics of multiple capsules in confined geometries.
• The study provides intuitive insights into complex fluid-structure interactions in micro-scale environments.