DEM-CFD simulation of fluid-particle flow in carrier-based Dry Powder Inhalers for pharmaceutical applications

Abstract

Dry powder inhalers (DPI) are medical devices speci cally engineered to ensure maximum and e ective delivery of active pharmaceutical ingredients (API) in powder form upon inhalation by a patient. In this work, highly challenging CFD{DEM simulations are utilized to deterministically track the motion of both carrier and API particles in dry powder formulations along their ow from the dose cup through the exit of a swirl- ow-based dry powder inhaler. To achieve this purpose, a combination of di erent solutions is adopted: a su ciently small time-step is coupled to scaled contact/adhesive interaction parameters; grid-based contact detection and uid-to-particle and particleto-

uid interpolation of the gas-solid interaction variables, i.e. gas velocity and voidage and drag force; a rolling friction model to allow for appropriate adhesion behaviour of the particles. Single phase air- ow, coupled air-carrier particle ow and coupled aircarrier- API particles are characterized in the device for di erent typical inhalation conditions. The aim is to investigate and gain detailed insight on all stages of the particles' lift-up, aero-dispersion, de-aggregation, interparticle and particle-wall collisions across the scales from few micron sized API powders to a commercial sized device. Thanks to a 4-way coupled CFD{DEM model, inertial, collisional, rotational and inter-particle adhesion e ects can be taken into account in modelling the coupled air and particle dynamics.