Surfactant spreading on thin viscous films: film thickness evolution and periodic wall stretch

Surfactant spreading on thin viscous films is of interest in the context of surfactant and liquid transport in the lungs, for both normal lung function and treatment of disease, as well as for many industrial processes. This paper presents experimental techniques for the measurement of film deformations due to spreading surfactant and for the investigation of the effects of periodic stretching of the wall supporting the thin film to mimic airway wall motion in the lung due to breathing. Additionally, we present results from both types of experiments, which agree favorably with our theoretical work.