Particle tracking schemes for micron particle deposition in a 90° pipe bend and nasal airway geometry

Abstract

Computational studies of micron particle deposition is used to predict inhaled particles through the nasal cavity for understanding drug delivery or toxicology risks. To ensure reliable results in future studies, this study evaluated particle tracking schemes and determined the most appropriate settings for predicting micron particle deposition in a pipe bend and nasal cavity geometry. Micron particles were injected into a fully developed 90° pipe bend under a turbulent flow regime with Reynolds number, $Re$ = 10,000, for comparison with existing data in the literature. Similarly, the micron particles were released into a more complex geometry, a human nasal cavity.

The study found that although the high-resolution tracking is the default and preferred option set out by Ansys-Fluent, the $5\mu m$ particle tested travelled further than when the high-resolution tracking was off. This was rectified by setting the wall nodal velocity to zero. All particle tracking schemes performed well and were suitable for predicting deposition for particle diameters $>5\mu m$, with high-resolution tracking and setting the wall nodal velocity to zero. However, the results become sensitive to the particle scheme when dealing with particle diameters ¡ $5\mu m$. The lower-order schemes overpredict deposition, while the higher-order schemes have zero deposition in the pipe bend unless the wall nodal velocity is set to zero. This study provides a list of recommended settings to best simulate particle deposition efficiency in Ansys Fluent (version 2023R2), although future releases of the CFD software may incorporate these settings as default options.