Near-Wake of a Semi-Submerged Cylinder

Near-wake of a semi-submerged cylinder. Flow past a semi-submerged cylinder at a relatively low Froude number, Fr = 0.66, generates a near-wake structure that varies substantially with time. At instant t1, the pattern of velocity vectors along the edge of the near-wake exhibits large-scale swirls; so-called reattachment to the free-surface does not appear to occur within the field of view. At instant t2, patterns of instantaneous velocity and vorticity suggest that instantaneous reattachment occurs at about the mid-region of the image; downstream of this location, instantaneous detachment from the free-surface is apparent, and the regions of high vorticity appear well below the surface. Re = 5,9990.