Visualizing the Flow Patterns in an Expanding and Contracting Pulmonary Alveolated Duct Based on Microcomputed...

Area of Science:

• Pulmonary biomechanics
• Fluid dynamics in biological systems

Background:

• Understanding airflow in the lungs is crucial for respiratory health.
• Alveolar structure and dynamics significantly impact gas exchange and particle transport.

Purpose of the Study:

• To visualize and analyze airflow patterns in an alveolated duct model.
• To investigate the influence of acinar deformation on these flow patterns during breathing motions.

Main Methods:

• Reconstruction of a compliant, scaled-up alveolated duct model from micro-CT scans.
• Particle image velocimetry (PIV) to visualize flow patterns.
• Controlled oscillation of fluid and duct volume to simulate respiratory cycles.

Main Results:

• Heterogeneous deformation induced distinct inspiration/expiration flow patterns.
• Recirculating flow regions within alveoli changed with the respiratory cycle.
• Alveolar geometry, like duct-mouth angle, affected flow patterns.
• Larger deformations at low Reynolds number (Re=0.03) shifted flow from recirculating to radial.

Conclusions:

• Alveolar flow patterns are sensitive to breathing-induced wall motions and deformation.
• Non-self-similar and heterogeneous wall motions may enhance particle mixing and deposition in the lungs.