Numerical studies of flows over liquid droplets on cylindrical fibers

Numerical calculations are carried out to study flows around liquid droplets held in place by cylindrical fibers. Two configurations were considered: (1) a droplet supported at the middle of a fiber that extends into the gas phase on both sides of the droplet and (2) a droplet suspended at the end of a fiber. Calculations are done for droplet Reynolds numbers based on droplet diameters of 0–100. The flow around a supported droplet loses its axisymmetry even for very thin support fibers. Significant changes are seen in flow patterns, separation lengths, and in pressure and friction drag coefficients. Maximum separation lengths increase almost linearly with support rod diameters. Where flow separation occurs, pressure drag coefficients increase while friction drag coefficients drop almost linearly with support rod diameters. For a suspended droplet, the flows at the droplet front resemble that seen for the supported droplet on one side and a free droplet on the other side. However, in the rear of the droplet, the flow interaction between the two sides creates a highly asymmetrical wake structure.

► The flow around a supported droplet loses its axisymmetry even for very thin fibers.
► Interactions between spherical and cylindrical wakes can lead to complex flows.
► The flow patterns around a droplet depend sensitively on the fiber geometry.