Propagation of an Air Finger Into a Fluid Filled Bifurcation

The occlusion of pulmonary airways can be caused by many respiratory diseases such as respiratory distress syndrome. It is believed that these occluded airways are reopened by the propagation of an air finger. The mechanics of airway reopening have been studied in-depth for an individual airway [1,2] without considering the frequent branching of pulmonary airways. The presence of a bifurcation leads to the question of whether the propagating air finger will clear both branches of the airway or will propagate through a single branch, leaving the other branch occluded. The propagation of a finite length liquid plug through a fixed bifurcation has been studied experimentally [3, 4]. We wish to develop a numerical model for the propagation of an air finger through bifurcating channel filled with a viscous fluid. In this model, the air finger is driven by a pressure difference between the parent channel and the two daughter branches. The presence of an additional pressure difference between the two branches can cause unsymmetrical splitting of the air finger and, above a critical pressure difference, prevent the clearance of both branches.