On the fluid forces acting on a circular cylinder with a triangle rib

In the preceding paper, we reported that the flows around a circular cylinder with a rib are classified into three patterns of re-attached, bi-stable and separated flow. In this paper, it was investigated experimentally the effect of Reynolds number and the scale of rib on the regions of located rib observed each flow patterns, and in case of the bi-stable flow pattern, in order to confirm that the re-attached and separated flow turn alternatively, the pressure distribution along the surface of a circular cylinder are measured. The following properties became evident after examining the experimental results. The value of Strouhal number based on the variation on lift force are small in case of the re-attached flow and large in case of separated flow in compared to a circular cylinder without rib and these values change by the ratio of the duration time of each flow patterns.