The flow between shrouded corotating disks

An experimental investigation of the flow between shrouded corotating disks has been performed. Three distinct regions of flow are observed: a solid body inner region near the hub, an outer region dominated by large counter-rotating vortices, and a boundary layer region on the shroud. The inner and outer regions were very two dimensional, with little variation in the direction parallel to the spin axis. The shroud boundary layer region was more three dimensional and contained a pair of toroidal vortices whose vorticity was in the ±θ direction. The effects of varying the Ekman number (ν/R2Ω) and the axial separation of the disks were studied. A decrease in the Ekman number or an increase of the axial separation of the disks resulted in fewer large vortices in the outer region yielding an increase in the relative motion in the inner region with a consequent increase in overall mixing. Corotating vortical structures were observed in the inner region at the largest axial separations and smallest Ekman numbers.