69th Annual Meeting of the APS Division of Fluid Dynamics (November 20, 2016 — November 22, 2016)

P0025: Organized modes in interacting vortex rings

• View Larger
• Download Original

Authors

• Jian Deng, Department of Mechanics, Zhejiang University, China
• Colm-cille Caulfield, BP Institute & DAMTP, University of Cambridge, UK

DOI: https://doi.org/10.1103/APS.DFD.2016.GFM.P0025

We investigate experimentally the interacting vortex rings induced by a sinusoidally oscillating disk. We vary the Keulegan-Carpenter numbers, between 0.3 and 1.5, and the Stokes numbers between 100 and 1200. Consistent with the global linear stability analysis, we observe organized modes with clearly countable numbers of waves emerging as sequential vortex rings shedding from the disk. These organized modes cover a wide range of wavenumbers, from m = 2 to m = 9, and can be further divided into two branches, which are distinguished by the phase properties of the vortical structures above and below the disk.