Electronic Resource
[S.l.]
:
American Institute of Physics (AIP)
Physics of Fluids
8 (1996), S. 1680-1682
ISSN:
1089-7666
Source:
AIP Digital Archive
Topics:
Physics
Notes:
It is now well known that the wake transition regime for a circular cylinder involves two modes of secondary three-dimensional instability (modes "A'' and "B''), depending on the regime of Reynolds number (Re). However, there exists a surprisingly large scatter in previous measurements of critical Re for the inception of the mode A instability (Re from 140 to 190) and in previous measurements of spanwise length scale. It is deduced in this work that the large variation in previous measurements concerning mode A are due to the presence of vortex dislocations. In the absence of such dislocations, we find an excellent agreement of the critical Re as well as spanwise wavelength of mode A with the linear secondary stability analysis of Henderson and Barkley [Phys. Fluids 8, 1683 (1996)]. We further demonstrate that these large-scale dislocations in wake transition are triggered at the sites of some of the vortex loops for mode A; they are an intrinsic feature of transition, independent of end conditions. These studies lead us to a new clarification of the possible flow states through wake transition, as follows. If one defines a Mode A* as (Mode A+Dislocations), then the route through transition appears to follow the scenario of wake modes: (2D→A→A*→B). © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.868949
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