scholarly journals Dependence on the initial conditions of scalar mixing in the turbulent wake of a circular cylinder

2004 ◽  
Vol 16 (8) ◽  
pp. 3161-3172 ◽  
Author(s):  
S. Beaulac ◽  
L. Mydlarski
Keyword(s):  
Circular Cylinder ◽  
Initial Conditions ◽  
Turbulent Wake ◽  
Scalar Mixing

Oscillatory flow past a circular cylinder in a rotating frame

1997 ◽  
Vol 345 ◽  
pp. 101-131
Author(s):  
M. D. KUNKA ◽  
M. R. FOSTER
Keyword(s):  
Circular Cylinder ◽  
Steady Flow ◽  
Stagnation Point ◽  
Oscillatory Flow ◽  
Numerical Solutions ◽  
Initial Conditions ◽  
Temporal Integration ◽  
Oncoming Flow ◽  
Flow Past ◽  
Rear Stagnation Point

Because of the importance of oscillatory components in the oncoming flow at certain oceanic topographic features, we investigate the oscillatory flow past a circular cylinder in an homogeneous rotating fluid. When the oncoming flow is non-reversing, and for relatively low-frequency oscillations, the modifications to the equivalent steady flow arise principally in the ‘quarter layer’ on the surface of the cylinder. An incipient-separation criterion is found as a limitation on the magnitude of the Rossby number, as in the steady-flow case. We present exact solutions for a number of asymptotic cases, at both large frequency and small nonlinearity. We also report numerical solutions of the nonlinear quarter-layer equation for a range of parameters, obtained by a temporal integration. Near the rear stagnation point of the cylinder, we find a generalized velocity ‘plateau’ similar to that of the steady-flow problem, in which all harmonics of the free-stream oscillation may be present. Further, we determine that, for certain initial conditions, the boundary-layer flow develops a finite-time singularity in the neighbourhood of the rear stagnation point.

scholarly journals Dynamical effect of the total strain induced by the coherent motion on local isotropy in a wake

2013 ◽  
Vol 720 ◽  
pp. 393-423 ◽  
Author(s):  
F. Thiesset ◽  
L. Danaila ◽  
R. A. Antonia
Keyword(s):  
Circular Cylinder ◽  
Large Scale ◽  
Bluff Body ◽  
Initial Conditions ◽  
Scale Up ◽  
Wake Flow ◽  
Total Strain ◽  
Coherent Motion ◽  
Square Cylinder ◽  
Local Isotropy

AbstractWe assess the extent to which local isotropy (LI) holds in a wake flow for different initial conditions, which may be geometrical (the shape of the bluff body which creates the wake) and hydrodynamical (the Reynolds number), as a function of the dynamical effects of the large-scale forcing (the mean strain, $ \overline{S} $, combined with the strain induced by the coherent motion, $\tilde {S} $). LI is appraised through either classical kinematic tests or phenomenological approaches. In this respect, we reanalyse existing LI criteria and formulate a new isotropy criterion based on the ratio between the turbulence strain intensity and the total strain ($ \overline{S} + \tilde {S} $). These criteria involve either time-averaged or phase-averaged quantities, thus providing a deeper insight into the dynamical aspect of these flows. They are tested using hot wire data in the intermediate wake of five types of obstacles (a circular cylinder, a square cylinder, a screen cylinder, a normal plate and a screen strip). We show that in the presence of an organized motion, isotropy is not an adequate assumption for the large scales but may be satisfied over a range of scales extending from the smallest dissipative scale up to a scale which depends on the total strain rate that characterizes the flow. The local value of this scale depends on the particular nature of the wake and the phase of the coherent motion. The square cylinder wake is the closest to isotropy whereas the least locally isotropic flow is the screen strip wake. For locations away from the axis, the study is restricted to the circular cylinder only and reveals that LI holds at scales smaller than those that apply at the wake centreline. Arguments based on self-similarity show that in the far wake, the strength of the coherent motion decays at the same rate as that of the turbulent motion. This implies the persistence of the same degree of anisotropy far downstream, independently of the scale at which anisotropy is tested.

Control of the turbulent wake flow behind a circular cylinder by asymmetric sectoral hydrophobic coatings

2021 ◽  
Vol 33 (12) ◽  
pp. 121703
Author(s):  
Anatoliy Lebedev ◽  
Konstantin Dobroselsky ◽  
Alexey Safonov ◽  
Sergey Starinskiy ◽  
Veronica Sulyaeva ◽  
...  
Keyword(s):  
Circular Cylinder ◽  
Turbulent Wake ◽  
Wake Flow ◽  
Hydrophobic Coatings

The turbulent wake of a circular cylinder rotating about the streamwise axis

1994 ◽  
Vol 16 (6) ◽  
pp. 375-384
Author(s):  
D. H. Wood ◽  
P. L. Peterson ◽  
P. D. Clausen
Keyword(s):  
Circular Cylinder ◽  
Turbulent Wake

scholarly journals Visualization of Multi-Scale Structures for Different Initial Conditions of Turbulent Wake Using Wavelets

2001 ◽  
Vol 21 (1Supplement) ◽  
pp. 203-206
Author(s):  
Hui LI ◽  
Yu ZHOU ◽  
Masahiro TAKEI ◽  
Yoshifuru SAITO ◽  
Kiyoshi HORII
Keyword(s):  
Initial Conditions ◽  
Turbulent Wake ◽  
Multi Scale ◽  
Scale Structures

Characteristics of vorticity fluctuations in a turbulent wake

1988 ◽  
Vol 189 ◽  
pp. 349-365 ◽  
Author(s):  
R. A. Antonia ◽  
L. W. B. Browne ◽  
D. A. Shah
Keyword(s):  
Circular Cylinder ◽  
Turbulent Wake ◽  
Probability Density Functions ◽  
The Self ◽  
Density Functions ◽  
Streamwise Vorticity ◽  
Local Isotropy ◽  
Vorticity Component ◽  
Vorticity Fluctuation ◽  
Made In

Measurements of the lateral components of the vorticity fluctuation have been made in the self-preserving turbulent wake of a circular cylinder. Each component was obtained separately using two X-wires separated in the appropriate lateral directions. The two velocity derivatives which make up the streamwise vorticity component were also determined but not simultaneously. An approximation to the streamwise vorticity was made from these measurements. Moments, probability density functions and spectra of the three vorticity components across the wake are presented and discussed. The high-wavenumber behaviour of the spectra is compared with calculations, based on local isotropy. Satisfactory agreement with the calculations is obtained for the lateral vorticity components over a significant high-wavenumber range. The approximated streamwise vorticity spectrum tends towards the isotropic calculation at very large wavenumbers.

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