Experiment on the Dynamics of a Thin Film Flow Coating on an Inclined Fiber

Abstract

We studied experimentally the dynamics of a thin film coating on a fiber with different inclined angles. This type of flow is asymmetric and accompanied by rich dynamics manifested via the formation and interaction of droplets. It is found that the dynamics of the coating flows exhibits three typical regimes, i.e., oscillatory flow, steady and unsteady pearl-like flows, at different flow rates. Interestingly, at a large inclined angle, the coating flow exhibits behaviors of droplets shedding in the convective regime at high flow rates. The steady and unsteady pearl-like flows correspond to the absolute and convective instabilities, respectively, and the oscillatory flow is due to the secondary instability of the travelling wave. From the viewpoint for nonlinear dynamics, the oscillatory wave is a solution of relative periodic orbit which has fixed temporal and spacial periods. We identified the transition boundaries between different flow regimes in the \(\theta -\overline{Q }\) plan.