Simulations at a newly derived reference model of the human lung

Based on an in-vitro preparation of an adult human lung combined with high-resolution tomography we developed a realistic graph representation of the bronchial tree of a particular human lung. The graph contains topological information about spatial coordinates, connectivities, diameters and branching angles of 1453 bronchi up to the 17th Horsfield order, and is characterized by asymmetric and multifractal properties. This geometrical model was the basis for the development of an unstructured, multiphase CFD model of the trachea and upper airways. This is directly relevant to research in that intricate anatomical system geometries are employed. Based on medical imaging data CFD modeling associated with complex moving geometries, multi-phase/multi-species physics, and turbulence is incorporated. We contrast this approach with the use of mass-transport equations that describe the gas transport axially. Results show that many of the transport processes within the airways depend quite sensitively on the geometry of the bronchial bifurcations and the structure of the boundaries.