78th Annual Meeting of the APS Division of Fluid Dynamics (Nov 23 — 25, 2025)

P003: Beyond parallel vortex shedding: Oblique vortex cores and vortex dislocation

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Flow over a circular cylinder at Re = 220 is known to exhibit mode-A instability having the dominant wavelength of 4d, where d is the cylinder diameter. Numerical simulations with a spanwise domain size (Lz) similar to this wavelength have shown parallel vortex shedding in the wake, resulting from restriction of possible spanwise length scales in the wake. With a much larger spanwise domain size, the flow in the wake becomes significantly different. For example, with Lz = 252d, flow in the near wake reveals very long oblique vortex core spanning over 45d, together with vortex dislocation. At a farther downstream, the dominant wavelength of the vortex core is about 10d. (Song, Yoon & Choi, PRF, 2025)