Reduction of Ekman circulation within Taylor-Couette flow

We demonstrate experimentally that independently rotating intermediary end-rings between the cylinders of a Taylor-Couette apparatus can be utilized to reduce friction-driven secondary flow, i.e. Ekman circulation. This allows for velocity profiles in a device of small aspect ratio to be less constrained by 'end effects', so that the resulting wide-gap flows can be made to have a radial distribution of circumferential velocity that resembles a narrow-gap Couette solution.