Simulation of the flow of cohesive particles in a model inhaler using a CFD/DEM model

The flow of cohesive particles in a model dry powder inhaler is studied using a soft sphere DEM model coupled with a dynamic LES CFD model. Collisions are modeled using a Hertzian model for the normal force, with a DMT model for cohesion, and using the model due to Mindlin and Deresiewicz for the tangential force. Calculations that simulate the inhalation of one dose show that small particles leave the inhaler faster than large particles and that large particles sometimes become trapped in a recirculation region that is established after the small particles have already left. The results also show that collisions are not important for particle-particle momentum exchange initially but become more important as the particles accelerate. (C) 2015 The Authors. Published by Elsevier Ltd.