Influence of wind on a viscous liquid film flowing down a thread

We investigate experimentally the effect of wind on the dynamics of a viscous liquid film flowing down a thread. The liquid film is well known to destabilize into an axisymmetric bead-like pattern in stagnant air. When the flowing thin film is exposed to side wind, the beads are pushed downstream of the wind, breaking the symmetry and leading to a modification of the film flow. The viscous dissipation in the liquid film decreases with increasing side wind, leading to a faster slide speed of the liquid beads. The inertia in the film is then increased, which can induce a regime shift, triggering an instability. When the film becomes unstable, it switches from a periodic pattern of equally sized liquid beads to an irregular film pattern where large beads collide with smaller ones.

Automated summary

We experimentally investigate the impact of wind on the dynamics of a viscous liquid film flowing down a thread. When exposed to side wind, the film's axisymmetric bead-like pattern is disrupted, leading to a modification of the flow. The increased inertia in the film can trigger an instability, causing a shift from periodic to irregular patterns.