Rivulet formation on an inclined cylinder and its effects on the near-wake

Wind rain tunnel experiments were performed in this paper to investigate the formation of water rivulet on the surface of an inclined stationary cylinder immerged in a uniform wind field and the effects of the rivulet on the near-wake of the cylinder. A digital video camera was used to record the formation of water rivulet for a series of cylinder inclination α, cylinder yaw angle β, incident free-stream wind velocity U ∞, and water flow rate m. The pictures were then analyzed to find the flow pattern and position of rivulet on the surface of the cylinder. A hot wire anemometer was used to measure wind speed near the cylinder, and a spectral analysis was then performed on the recorded data to investigate the effects of water rivulet on the near-wake of the cylinder. It was found that the formation of water rivulet depends on the parameters m, U∞, α, and β significantly. Water rivulets can be formed on the cylinder surface only in the range of 0° ≤ β ≤ 90° for U ∞ = 8 - 15 m/s. Water rivulets seem to locate near flow separation points and move circumferentially. It was also found that fluid dynamics associated with wind-water-structure interaction could be quite different from that without the involvement of water rivulet.