Dewetting dynamics in gel-coated tubes in microgravity

Treatment of respiratory distress syndrome (RDS) often relies on the delivery of liquid drugs from the trachea to the lungs. To determine the role of mucus in the transport of the liquid plug, we conduct dewetting experiments with partially wetting fluids in cylindrical gel-coated tubes. We rely on the microgravity environment onboard the International Space Station to study the dewetting in glass tubes of centimeter-scale diameter. We conduct a series of experiments to characterize the influence of the gel thickness, tube diameter, and fluid properties on the formation and stability of a trailing liquid film. For each experiment, the tube is initially filled with liquid. The liquid is then pushed out of the tube by air and injected at a constant flow rate. The experimental results indicate that the thickness of the liquid trailing film and dewetting rate depend on tube diameter and gel thickness.