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FERGUL - Fluids Engineering Research Group at the University of Liverpool. The video shows the development of vortex breakdown in a swirling pipe flow. The experiment consists of two smoothly joined pipe sections that can be rotated independently about the same axis. In this clip, the pipe on the left hand side of the video is rotating whilst the pipe on the right hand side remains stationary. The flowrate through the pipe remains fixed (giving a Reynolds number of 25 based on the average velocity and pipe diameter) whilst the rotational speed of the left pipe is slowly increased. Once the swirl imparted to the flow goes above a critical value then flow reversal - so-called “vortex breakdown“ occurs. For full details see D. J. C. Dennis, C. Seraudie and R. J. Poole “Controlling vortex breakdown in swirling pipe flows: Experiments and simulations“. Phys. Fluids 26, 053602 (2014)
