Investigation of the dynamics of a coating flow on a vertical fiber immersed in surrounding liquid phase

In the present paper, we investigated experimentally the dynamics of coating flow on a vertical fiber immersed in a liquid phase environment. This flow exhibits rich dynamics which is different from the coating flow in air. In the experiments, it is found that the dynamics of immersed coating flow at different flow rates exhibited three flow regimes, i.e., highly regular beads chain, bound state and beads-like flow with irregular coalescence. The regular and irregular beads-like flows correspond to absolute instability and convective instability, respectively. The bound state flow occurs at the boundary of absolute instability and convective instability. The behavior of immersed coating flow is examined by analyzing the spatiotemporal diagram. In addition, we quantitatively investigated three important characteristic parameters of the immersed coating flow, i.e., wave thickness, wave spacing and wave speed in different flow regimes.