Flow and particle deposition in the Turbuhaler: a CFD simulation

Area of Science:

• Engineering
• Pharmaceutical Sciences
• Fluid Dynamics

Background:

• Accurate simulation of airflow and particle transport is crucial for optimizing dry powder inhaler (DPI) performance.
• Understanding particle deposition within DPI devices impacts drug delivery efficiency and patient outcomes.
• Computational fluid dynamics (CFD) offers a powerful tool for analyzing complex flow phenomena in DPIs.

Purpose of the Study:

• To simulate and analyze steady-state airflow and particle deposition within a commercial DPI (Turbuhaler) using CFD.
• To evaluate the performance of various flow models (laminar, k-ε, k-ε RNG, k-ω SST, LES) in predicting DPI behavior.
• To determine the influence of pressure drop and particle characteristics on deposition patterns.

Main Methods:

• Steady-state flow in the DPI was modeled using the Navier-Stokes equations solved with commercial CFD software.
• Particle motion and deposition were simulated using a Eulerian-fluid/Lagrangian-particle approach.
• The transitional k-ω SST model was identified as the most accurate for turbulent flow, validated against Large Eddy Simulation (LES) and experimental pressure drop data.

Main Results:

• The transitional k-ω SST model demonstrated results closely matching LES and experimental pressure drop data.
• Simulations covered a range of mouthpiece pressure drops (800-8800 Pa) and particle sizes (0.5-20 μm).
• CFD predictions for local and total particle deposition showed good agreement with available experimental data.

Conclusions:

• The transitional k-ω SST turbulence model is a reliable choice for simulating airflow and particle deposition in DPIs.
• CFD simulations provide valuable insights into the factors governing particle deposition within DPI devices.
• The study validates the use of CFD as an effective tool for the design and optimization of DPIs.