Numerical Study on Particle Adhesion in Dry Powder Inhaler Device

Abstract

This study investigated the particle adhesion mechanism in a capsule of dry powder inhaler (DPI) based on a combined computational fluid dynamics and discrete element method (CFD-DEM) approach. In this study, the Johnson-Kendall-Roberts (JKR) theory was selected as the adhesion force model. The simulation results corroborated the experimental results-numerous particles remained on the outlet side of the capsule, while a few particles remained on the inlet side. In the computer simulation, the modeled particles were placed in a capsule. They were quickly dispersed to both sides of the capsule, by air fed from one side of the capsule, and delivered from the air inlet side to the outlet side of the capsule. It was confirmed that vortex flows were seen at the outlet side of the capsule, which, however, were not seen at the inlet side. Numerous collisions were observed at the outlet side, while very few collisions were observed at the inlet side. These results suggested that the vortex flows were crucial to reduce the amount of residual particles in the capsule. The original capsule was then modified to enhance the vortex flow in the area, where many particles were found remaining. The modified capsule reduced the number of residual particles compared to the original capsule. This investigation suggests that the CFD-DEM approach can be a great tool for understanding the particle adhesion mechanism and improving the delivery efficiency of DPIs.

Discrete Element Method Evaluation of Triboelectric Charging Due to Powder Handling in the Capsule of a DPI

“…Zhu et al [ 35 ] studied the contact electrification effect of selected API agglomerates in the Turbuhaler ® , finding a reduction in inhaler efficiency due to the triboelectrification of powders. Specific numerical studies on the motion of particles in the capsule of capsule-based DPIs are available in the literature [ 36 , 37 , 38 , 39 ], but the effects of charges generated upon contact on the release of powder from the capsule itself are not taken into account. Most of previous works in DPI applications focus on the influence of electrostatic interactions between previously charged particles, rather than the charge buildup process, and the charging of capsule walls is typically neglected.…”

A real-time and modular approach for quick detection and mechanism exploration of DPIs with different carrier particle sizes

“…Moreover, it was time and labor consuming to conduct NGI tests since the complicated operation and followed up quantification required an entire day for only one measurement, and thus severely hampered the efficiency of the industrialization processes. CFD-DEM model was a powerful tool to simulate the behavior of fluid–particle interactions 10 , and was successfully employed in DPIs to aid the analyzing particle motion in the inhaler devices 11 , throat 12 and bronchi 3D models 13 , 14 . However, the crucial physical properties, such as the particle shape, surface roughness and particle size distribution, were often over simplified in CFD-DEM model.…”

CFD-DEM Coupling Model for Deposition Process Analysis of Ultrafine Particles in a Micro Impinging Flow Field

“…Although the computational time is long, which limits the particle size and particle number, parallel processing capability is an advantage of the DEM method to scale up the particle number [ 16 ]. CFD-DEM approach has been applied to simulate particle behavior in the impactor [ 17 ]. Ohsaki et al [ 18 ] simulated the behavior of fluid and particles in the cascade impactor using the CFD-DEM method with Johnson–Kendall–Roberts (JKR) theory [ 19 ].…”