Journal
JOURNAL OF FLUID MECHANICS
Volume 919, Issue -, Pages -Publisher
CAMBRIDGE UNIV PRESS
DOI: 10.1017/jfm.2021.406
Keywords
bifurcation; vortex shedding; flow-structure interactions
Categories
Funding
- Australian Government through Cooperative Research Centres Project (CRC-P) grant [CRC-P57367]
- Total Marine Technology Pty Ltd
- Australian Government
- Government of Western Australia
Ask authors/readers for more resources
Numerical investigation on wake transitions behind an isolated cube revealed four different flow regimes and their evolution patterns. The study also identified the transition mechanisms between vortex shedding states and the critical Reynolds numbers for bifurcations to different regimes.
Wake transitions behind an isolated cube are investigated numerically over a range of Reynolds number (Re) 1-400. Four flow regimes, namely the orthogonal symmetry-steady (1 <= Re <= 205), planar symmetry-steady (PSS, 210 <= Re <= 250), hairpin-vortex shedding (HS, 255 <= Re <= 305) and chaotic vortex shedding (Re >= 310) regimes, are identified according to spatial symmetries and temporal development of the flow. A weakly nonlinear stability analysis, through a coupled pitchfork bifurcation model proposed in the present study, reveals that the bifurcation to the PSS regime is supercritical and the planar symmetry is retained in the PSS regime because stable points (four) exist only on the two symmetry planes perpendicular to the side faces of the cube. The supercritical Hopf bifurcation to the HS regime is induced by the excessive accumulation of circulation in the downstream tips of merged streamwise vortex tubes behind the cube that subsequently attract the vortex tubes of opposite signs to cut the tips off from them, leading to alternate shedding of streamwise vortex tubes. The planar symmetry observed in the PSS regime is preserved in the three vortex shedding states identified in the HS regime, i.e. single-frequency shedding (255 <= Re <= 280), quasi-periodic shedding (282 <= Re <= 285) and the high-order synchronised shedding (HS2, 289 <= Re <= 305). A cascade of period doubling and period halving is discovered in the HS2 state, prior to the flow bifurcation to the chaotic vortex shedding regime, where the planar symmetry is broken. The critical Re values for the bifurcations to PSS and HS regimes are estimated to be Re approximate to 207.0 and 252.0, respectively, through linear interpolation of the growth rate of flow instabilities.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available