Anatomically based three-dimensional model of airways to simulate flow and particle transport using computational fluid dynamics

Abstract

We have studied gas flow and particle deposition in a realistic three-dimensional (3D) model of the bronchial tree, extending from the trachea to the segmental bronchi (7th airway generation for the most distal ones) using computational fluid dynamics. The model is based on the morphometrical data of Horsfield et al. (Horsfield K, Dart G, Olson DE, Filley GF, and Cumming G. J Appl Physiol 31: 207-217, 1971) and on bronchoscopic and computerized tomography images, which give the spatial 3D orientation of the curved ducts. It incorporates realistic angles of successive branching planes. Steady inspiratory flow varying between 50 and 500 cm(3)/s was simulated, as well as deposition of spherical aerosol particles (1-7 microm diameter, 1 g/cm(3) density). Flow simulations indicated nonfully developed flows in the branches due to their relative short lengths. Velocity flow profiles in the segmental bronchi, taken one diameter downstream of the bifurcation, were distorted compared with the flow in a simple curved tube, and wide patterns of secondary flow fields were observed. Both were due to the asymmetrical 3D configuration of the bifurcating network. Viscous pressure drop in the model was compared with results obtained by Pedley et al. (Pedley TJ, Schroter RC, and Sudlow MF. Respir Physiol 9: 387-405, 1970), which are shown to be a good first approximation. Particle deposition increased with particle size and was minimal for approximately 200 cm(3)/s inspiratory flow, but it was highly heterogeneous for branches of the same generation.

Steady flow through a realistic human upper airway geometry

“…The majority of applications in the literature concentrate around the topic of particle transport in upper and lower human airways. Studies on this topic include application to spray dynamics and smoke particles [36][37][38][39][40][41][42][43][44][45][46]. In these studies, in addition to a fluid dynamics algorithm, an efficient way of tracking the particles is essential.…”

Validation of CFD predictions of flow in a 3D alveolated bend with experimental data

“…In the recent years, several CFD studies of aerosol transport in lung airspaces have been performed (Harrington et al, 2006;Nowak et al, 2003;van Ertbruggen et al, 2005) where accurate descriptions of the flow field were coupled to simplified tracking algorithms to determine deposition patterns within the models. The absence of direct in-vivo measurements in the lung made it almost impossible to validate numerical predictions from these models.…”

“…Many CFD studies have used complex realistic models of the lung (Harrington et al, 2006;Nowak et al, 2003;van Ertbruggen et al, 2005). These models provided detailed information on the flow field and deposition patterns within lung structures.…”

Workshop on the Sources, Quantification and Health Implications of Bioaerosols Workshop Report

“…Moreover if bioaerosols interact with living creatures via inhalation then the dispersion of the bioaerosol within the respiratory system also needs to be considered. The respiratory system can efficiently filter various aerosol sizes through impaction and diffusion (Van Ertbruggen et al, 2005).…”