Orderly flow structures in grid-generated turbulence with background rotation

An experimental study of orderly flow structures in turbulence with background rotation is presented. Experiments are performed on grid-generated turbulent flows of water filling a rotating tank. Flow velocity fields are visualized using a tracer-particle technique and measured using a laser Doppler velocimeter. Six types of orderly flow structures are found to depend on the Rossby and Reynolds numbers. The effect of the background rotation on the mean circumferential velocity, turbulence intensity and wavenumber spectrum of the flow is investigated. When the Rossby number is small, the variations of the mean velocity and turbulence intensity with depth are kept small, and the deviation of the wavenumber spectrum from the -5/3 law is noticeable.