CFD simulation of particle deposition in a reconstructed human oral extrathoracic airway for air and helium–oxygen mixtures

Improved prediction of intersubject variability in extrathoracic aerosol deposition using algebraic correlations

“…While the characteristic diameter of the Golshahi et al (2013) model provides a global measure of extrathoracic airway dimension, it does not allow consideration of differences in localized shape within the oropharyngeal region between and among subjects. Because such localized inter-and intra-subject variations in geometry are known to significantly influence deposition Sandeau et al 2010;Katz et al 2013), it is perhaps unsurprising that the prediction of deposition on a subject-specific basis given knowledge of only one characteristic diameter is relatively inaccurate, a conclusion Table 2. Values used in the calculation of deposition for the in vivo data of Yang et al (2017).…”

Direct numerical simulations of flow in realistic mouth–throat geometries

“…A number of Reynolds-averaged Navier-Stokes (RANS) (Zhang et al, 2002;Heenan et al, 2003;Kleinstreuer & Zhang, 2003;Matida et al, 2004;Jayaraju et al, 2007;Sandeau et al, 2010) and large eddy simulation (LES) studies (Matida et al, 2006;Jayaraju et al, 2008;Debhi, 2011;Cui & Gutheil, 2011) have been reported in the literature. However, accurate prediction of the flow field remains a challenge due to the complexity of the flow in the extrathoracic airways and the limitations of RANS and LES turbulence models.…”

“…Studies which have focused on accurately modelling the geometry have employed RANS turbulence models (Jayaraju et al, 2007;Sandeau et al, 2010) which do not resolve any of the scales in the flow, but rather model the fluctuations, usually based on empirical data obtained from canonical and often equilibrium flows. The flow in the complex extrathoracic airways differs significantly from a canonical duct flow however, and the inaccurate modelling of the fluctuations, which cause dispersion, affects the prediction of deposition.…”

Optimal Branching Asymmetry of Hydrodynamic Pulsatile Trees

“…A branching defines the beginning of a new generation. The tracheobronchial tree starts at the trachea (generation 0) and ends in the terminal bronchioles (around generation 15) at the entrance of the acini [1]. Since no gas exchanges take place in the tracheobronchial tree, its volume is referred to as the dead space volume (DSV).…”