(94h) One-Way Coupled CFD-DEM Analysis of Particulate Flows in a Monodose Dry Powder Inhaler

In this study, we perform a one-way coupled computational fluid dynamics (CFD) and discrete element method (DEM) simulation of a spinning, filled capsule in a monodose dry powder inhaler (DPI). Commercial software packages ANSYS Fluent and Rocky DEM are used for performing, respectively, the CFD and DEM computations. The coupled multiphysics model is used to primarily study the mechanisms by which powder is discharged from the capsule as well as factors that lead to in-capsule and in-device powder retention. Model results suggest that powder discharge from the capsule is influenced by two opposing forces: those that result from the centrifugal acceleration that drives the powder to the capsule ends, and those that result from the high-velocity air at the capsule ends that impedes powder from discharging from the capsule. In addition, air flow into the capsule, the amount of which increases as the capsule becomes more empty, combined with the dome shape of the capsule ends, causes a small amount of powder to be inevitably retained within the capsule. In addition, we demonstrate that the model may be used to perform parametric studies to determine solid formulation properties critical to reducing in-capsule powder retention, as well as device design modifications that may minimize in-device powder retention. The limitations of the one-way coupled approach, determined through comparing quantities of interests with those predicted from a two-way coupled model, will also be discussed.