A multiscale bidirectional coupling framework.

Area of Science:

• Computational fluid dynamics (CFD)
• Multiscale modeling
• Respiratory mechanics

Background:

• The lung's complex geometry across scales presents computational challenges for modeling airway mechanics.
• Linking lower-scale ordinary differential equations (ODEs) to 3D models requires robust iterative communication.

Purpose of the Study:

• To develop and validate a novel multiscale computational framework for bidirectionally coupling 3D CFD models with ODE systems.
• To assess the accuracy and computational efficiency of the coupled framework.

Main Methods:

• A novel multiscale framework was developed to couple 3D CFD models with ODE systems.
• Weibel lung models (4 and 8 generations) were used for validation, with truncated portions represented by RL circuits.
• Flow characteristics were compared between coupled and uncoupled full 3D CFD models.

Main Results:

• The coupled CFD-ODE models demonstrated high accuracy, with differences in mass flux and pressure <2.43% compared to uncoupled models.
• Flow characteristics at key locations showed good agreement between coupled and uncoupled simulations.
• The computational cost of ODE coupling was comparable to uncoupled 3D-CFD due to Krylov subspace reuse.

Conclusions:

• The developed multiscale framework effectively couples 3D CFD and ODE models for lung mechanics.
• The framework offers an accurate and computationally efficient approach for simulating complex respiratory dynamics.