FSI Analysis of the Human Trachea under Impedance-Based Boundary Conditions

This work is focused on the analysis of a healthy and a stenotic human trachea with aim to study flow patterns, wall stresses and deformations under physiological and pathological conditions. The two analyzed tracheal geometries, which include the first bifurcation after the carina, were obtained from computed tomography (CT) images of a healthy and a diseased patient respectively. Numerical simulations were performed through a finite element-based commercial software package, using a fluid-solid interaction (FSI) approach. Tracheal wall was modeled as a fiber reinforced hyperelastic material in which we modeled the anisotropy due to the orientation of the fibers. Impedance-based pressure waveforms were computed using a method originally developed for the cardiovascular system, where the resistance of the respiratory system was calculated taking into account the entire bronchial tree, modeled as binary fractal network. Performed simulations show the possibility of analyzing flow and wall behavior for healthy and pathological tracheas, being a useful tool capable to evaluate quantities that cannot be assessed in vivo, like shear and wall stresses, pressure drop and flow patterns and to derive parameters which in the future could help clinical decisions and improve surgical outcomes.