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Combining Computational Fluid Dynamics and Discrete Element Method Modeling with Experiments to Predict Dry Powder Inhaler Performance

Thalberg K, Nguyen D, Niklasson-Björn I, Remmelgas J, van Wachem B.

RDD Europe 2019. Volume 1, 2019: 43-50.

Abstract:

A multi-scale simulation model has been developed to predict the behavior of adhesive mixtures in dry powder inhalers (DPIs). In this work, fully coupled computational fluid dynamics-discrete element method (CFD-DEM) simulations were carried out in two different device geometries, at two air flow rates, using adhesive mixtures with different surface energy levels. The results were compared to experimental data for two corresponding formulations with a focus on the aerosolized fine particle fraction (FPF). It was found that experimentally obtained surface energies could not be used for the prediction of the observed fine particle fractions. We then derived the apparent surface energies of the two formulations from their aerosol performance in the first device, but again found the FPF could not be predicted in the second device for one of the formulations. We found that in order to predict formulation performance in different inhalers at different flow rates, a distribution of apparent surface energies is needed by the model. This is in agreement with colloidal probe measurements of the active pharmaceutical ingredient (API)-carrier interaction in adhesive mixtures