Coupled 1d-3d-simulation of the oscillatory flow in an idealised bronchial tree

Abstract

A one-dimensional model for the numerical simulation of oscillating fluxes in the lung, implemented in C++, was extended by modeling the local elastic behavior of the lung. The model was used with praxis-related tidal volumes and oscillatory frequencies, which represent the input parameters. The effect of the extension on the calculated pressure course of the one-dimensional model was analyzed by evaluating the results. The extended model was then implemented as an boundary condition in the finite volume based flow solver OpenFOAM for modeling the behavior of the bronchial tree below generation seven. This boundary condition was used to calculate coupled 1d-3d-simulations of oscillating flows in a pipe. Herein, geometric dimensions of the pipe match those of the seventh generation of the bronchial tree. The simulations are calculated with 41 < Re 720 and 0.3 < Wo < 15. Those parameters span the realistic range for high-frequency oscillatory ventilation in the seventh generation. In the analysis of the results it is shown that it is important to describe the non resolved parts of the bronchial tree with a dynamic boundary condition.