Computational fluid dynamics (CFD) and direct visualization studies of aerosol release from two cyclohaler-type dry powder inhalers

Aerosol flow pattern and emission obtained in two variants of aerolizer/cyclohaler DPI was modeled using CFD at the standard airflow rate of 100 L/min. Airflow was analyzed with k-ε turbulence model on the unstructured numerical meshes with more than 0.5 million elements. Dynamics of aerosol particles with the size of 1-10 μm were analyzed with the Lagrangian approach. The results of simulations showed that aerosol particles get stronger rotation and higher centrifugal velocities in the DPI with the longer mouthpiece. This inertial effect results in a higher deposition of fine particles (2-4 μm) in the inhaler mouthpiece and in the adjacent outer space. Theoretical predictions were verified by high-speed video recordings of the aerosol cloud released from both studied DPIs. It is concluded that the application of the modified cyclohaler with the short mouthpiece may be beneficial for a more efficient delivery of fine particles to the lower respiratory tract.