Films in narrow tubes

What is it about?

We consider liquid films lining the inner surface of a narrow cylindrical tube and their interaction with a second fluid filling the core. Such a situation occurs in pulmonary capillaries wetted by a mucus film that can collapse and impede normal breathing. We study this collapse, when interfacial perturbations grow sufficiently large to reach the tube axis and form a liquid bridge, with a long-wave model. Different fluid combinations and the effect of an oscillating core flow are considered.

Featured Image

Why is it important?

Our low-dimensional model enables calculations at much reduced computational cost, providing an efficient method for the quantitative prediction of critical phenomena such as liquid bridge formation. In contrast to simpler models, predictions remain accurate for fluid combinations that are not dominated by viscosity and inertia is relevant, e.g. water/air. Long-time flooding may occur after growth has been halted by viscous blocking due to sliding liquid collars resulting from symmetry breaking.