Pressure Loss Coefficients for Asymmetric Bifurcations of Pulmonary Airways with Predetermined Flow Distributions

Abstract

Computational Fluid Dynamics simulations of inspiratory airflow in asymmetric bifurcations have been performed in order to determine the influence of the asymmetry and Reynolds number on pressure losses over a physiologically relevant range for pulmonary airways; thus the results of this work can contribute to the understanding of respiratory ventilation in health and in disease. A key a priori insight to the design of the study is that the flow distribution in respiratory bifurcations can be largely independent of the local losses; and therefore, is predetermined by the boundary conditions in these calculations. The results, presented in the form of pressure loss coefficients, indicate that asymmetry and downstream conditions are significant for severe restrictions and laminar flow; but are relatively insignificant for turbulent flow conditions and for flow through the healthy branch.