Visualization of sudden-start flow between two concentric rotating cylinders with finite length

Numerical simulation and visualization are performed to investigate the developing processes of flows between two concentric rotating cylinders. The length of the cylinders is finite and the end walls are fixed. Initially the fluid is at rest, and the inner cylinder suddenly begins to rotate. Various flow modes appear in this flow. Developments of the flow to these modes are examined and the physical explanation for the transient process is presented. The processes are classified into some types. At low Reynolds numbers, vortices begin to grow on end walls. When the Reynolds number is higher, the centrifugal instability brings first vortices around the mid-plane in the axial direction. Some final modes are established via an intermediate mode, and some other modes are attained after merging and vanishing of vortices.