Investigation of flow dynamics of thin viscous films down differently shaped fibers

Abstract

The flow dynamics of a thin viscous film down on a fiber is associated with a variety of industrial applications. In this paper, we experimentally investigate the flow behaviors of a thin film falling on differently shaped fibers. For a spiral fiber, flow behaviors show three typical flow regimes as the cylindrical fiber, which indicates the isolated regime, Rayleigh–Plateau regime, and convective regime. However, the transition process of various fiber shapes is distinctively different. Unlike the cylindrical fiber, flow on a spiral fiber exhibits a wider range of flow rate in the Rayleigh–Plateau regime, which is helpful for the precise control of flow patterns in a relatively stable regime. We further quantitatively investigate three important characteristic parameters of flow dynamics of a spiral fiber, i.e., bead velocity, thickness, and spacing. Results reveal that a thin film on a spiral fiber has a higher bead velocity, larger bead thickness, and larger bead spacing. Our findings provide important insights for understanding flow dynamics of a thin viscous film down on shaped fibers, which may also inspire coating flow control methods in various applications.