Effects of Injection Size Distribution on the Aerosol Deposition within Human Airways

Aerosolized drug delivery within the human airways using metered-dose inhalers (MDI) is an effective strategy for treating pulmonary diseases. The particle size distribution from MDI is usually polydisperse, which exhibits differences in aerosol deposition compared to a monodisperse distribution. In this study, we examine the effects of injection size distribution on the local and global deposition within a realistic human airway model based on the SimInhale benchmark case, comprising the extrathoracic and intrathoracic airways. We employ the well-established Eulerian-Lagrangian framework to perform large-eddy simulation (LES) under a one-way coupled regime. First, the LES results from the monodisperse injection with the particle size of 4.3 μm at the inlet bulk Reynolds number of 3745 are compared with reference results. Afterward, we compare the monodisperse and polydisperse distributions with the same mean particle size and different values of geometric standard deviation representative of MDI. For the polydisperse injection, we consider Rosin-Rammler, Gaussian, and uniform types of distribution models. Lastly, we perform uncertainty quantification (UQ) of the aerosol deposition under the polydisperse injection scenario by employing a non-intrusive framework relying on the polynomial chaos expansion-based surrogate modeling technique. For the UQ study, the particle size is considered as the uncertain parameter, and the aerosol deposition is regarded as the quantity of interest.