Effects of Improved Near-Wall Modeling on Micro-Particle Deposition in Oral Airway Geometries

Direct Lagrangian particle tracking provides an effective method for simulating micro-aerosol deposition in the upper respiratory airways. However, Xi and Longest [1] have shown that errors occurred in the predicted deposition rates of smaller particles in comparison to measurements. Matida et al. [2] attributed a similar discrepancy to the assumption of isotropic turbulent fluctuations near the wall. Matida et al. [2] implemented a near-wall anisotropic turbulence model and reported significantly improved agreement with experimental data. Longest and Xi [3] investigated nanoparticle deposition in oral airway models and showed that a Lagrangian transport model with a user-defined near-wall interpolation (NWI) algorithm provided an effective approach to accurately predict deposition in comparison to available experimental results. It is proposed that implementing both an anisotropic turbulence model with a NWI routine may further improve agreement between numerical and experimental results. The objective of this study is to evaluate the effect both near-wall anisotropic and interpolation models on regional deposition values in the oral airway geometry. Comparisons will be made to available in vitro test results. Models considered will include (1) the anisotropic correction only, and (2) anisotropic and NWI routines.