A study of unsteady wake flows past a two-dimensional square cylinder with and without planar jet injection into the vortex formation region

1995 ◽  
Vol 55 (3) ◽  
pp. 187-210 ◽  
Author(s):  
P. Koutmos ◽  
C. Mavridis ◽  
D. Papailiou
Keyword(s):  
Vortex Formation ◽  
Two Dimensional ◽  
Square Cylinder ◽  
Jet Injection ◽  
Formation Region ◽  
Wake Flows ◽  
Planar Jet ◽  
Unsteady Wake

External Excitation of Planar Jets

1972 ◽  
Vol 39 (4) ◽  
pp. 883-890 ◽  
Author(s):  
D. O. Rockwell
Keyword(s):  
Reynolds Number ◽  
Vortex Formation ◽  
External Excitation ◽  
Formation Region ◽  
Initial Formation ◽  
Planar Jet ◽  
Periodic Disturbances ◽  
Wide Range

A planar jet was subjected to transverse periodic disturbances of appropriate dimension-less frequency such that the vortex growth of the jet could be controlled for a wide range of jet Reynolds number (1860 to 10,800). Changes in the apparent time mean characteristics of the jet in its initial formation region, due to the applied disturbances, are related to the behavior of vortices. The processes of vortex formation, growth, and coalescence in the initial formation region are portrayed. The alterations of these processes as a function of the dimensionless applied disturbance are classed into regimes identified with respect to the natural breakdown state of the jet.

Theoretical and Experimental Study of Development of Two-Dimensional Steady and Unsteady Wakes Within Curved Channels

1995 ◽  
Vol 117 (4) ◽  
pp. 593-598 ◽  
Author(s):  
M. T. Schobeiri ◽  
K. Pappu ◽  
J. John
Keyword(s):  
Equations Of Motion ◽  
Theory Development ◽  
Detailed Comparison ◽  
Wake Flow ◽  
Turbulent Shear ◽  
Two Dimensional ◽  
Curved Channel ◽  
Mean Velocity ◽  
Wake Flows ◽  
Unsteady Wake

Development of steady and periodic unsteady wake flows downstream of stationary and rotating cylindrical rods within a curved channel under zero longitudinal pressure gradient is theoretically and experimentally investigated. Wake quantities such as the mean velocity and turbulent fluctuations in longitudinal and lateral directions, as well as the turbulent shear stress, are measured. For the nondimensionalized velocity defect, affine profiles are observed throughout the flow regime. Based on these observations and using the transformed equations of motion and continuity, a theoretical frame work is established that generally describes the two-dimensional curvilinear wake flow. To confirm the theory, development of steady and periodic unsteady wakes in the above curved channel are experimentally investigated. The detailed comparison between the measurement and the theory indicates that the complex steady and unsteady wake flows are very well predicted.

Flow regimes for a square cross-section cylinder in oscillatory flow

2017 ◽  
Vol 813 ◽  
pp. 85-109 ◽  
Author(s):  
Feifei Tong ◽  
Liang Cheng ◽  
Chengwang Xiong ◽  
Scott Draper ◽  
Hongwei An ◽  
...  
Keyword(s):  
Circular Cylinder ◽  
Cross Section ◽  
Oscillatory Flow ◽  
Vortex Formation ◽  
Flow Regimes ◽  
Oscillation Period ◽  
Marginal Stability ◽  
Two Dimensional ◽  
Square Cylinder ◽  
Vortex Formation Time

Two-dimensional direct numerical simulation and Floquet stability analysis have been performed at moderate Keulegan–Carpenter number ($KC$) and low Reynolds number ($Re$) for a square cross-section cylinder with its face normal to the oscillatory flow. Based on the numerical simulations a map of flow regimes is formed and compared to the map of flow around an oscillating circular cylinder by Tatsuno & Bearman (J. Fluid Mech., vol. 211, 1990, pp. 157–182). Two new flow regimes have been observed, namely A$^{\prime }$ and F$^{\prime }$. The regime A$^{\prime }$ found at low $KC$ is characterised by the transverse convection of fluid particles perpendicular to the motion; and the regime F$^{\prime }$ found at high $KC$ shows a quasi-periodic feature with a well-defined secondary period, which is larger than the oscillation period. The Floquet analysis demonstrates that when the two-dimensional flow breaks the reflection symmetry about the axis of oscillation, the quasi-periodic instability and the synchronous instability with the imposed oscillation occur alternately for the square cylinder along the curve of marginal stability. This alternate pattern in instabilities leads to four distinct flow regimes. When compared to the vortex shedding in otherwise unidirectional flow, the two quasi-periodic flow regimes are observed when the oscillation frequency is close to the Strouhal frequency (or to half of it). Both the flow regimes and marginal stability curve shift in the $(Re,KC)$-space compared to the oscillatory flow around a circular cylinder and this shift appears to be consistent with the change in vortex formation time associated with the lower Strouhal frequency of the square cylinder.

Isothermal and non-premixed turbulent reacting wake flows past a two-dimensional square cylinder

1998 ◽  
Vol 17 (1-2) ◽  
pp. 90-99 ◽  
Author(s):  
C. Mavridis ◽  
A. Bakrozis ◽  
P. Koutmos ◽  
D. Papailiou
Keyword(s):  
Two Dimensional ◽  
Square Cylinder ◽  
Wake Flows

STUDY OF NON-ISOTHERMAL TWO-DIMENSIONAL FLOW OVER A SQUARE CYLINDER IMMERSED IN A CHANNEL

2019 ◽  
Author(s):  
Gabriel Machado dos Santos ◽  
Ítalo Augusto Magalhães de Ávila ◽  
Hélio Ribeiro Neto ◽  
João Marcelo Vedovoto
Keyword(s):  
Two Dimensional ◽  
Square Cylinder ◽  
Dimensional Flow ◽  
Two Dimensional Flow

scholarly journals Dynamical thermalization and vortex formation in stirred two-dimensional Bose-Einstein condensates

2008 ◽  
Vol 78 (6) ◽  
Author(s):  
T. M. Wright ◽  
R. J. Ballagh ◽  
A. S. Bradley ◽  
P. B. Blakie ◽  
C. W. Gardiner
Keyword(s):  
Vortex Formation ◽  
Two Dimensional ◽  
Bose Einstein

Structural characteristics of a developing turbulent planar jet

1986 ◽  
Vol 163 ◽  
pp. 227-256 ◽  
Author(s):  
F. O. Thomas ◽  
V. W. Goldschmidt
Keyword(s):  
Large Scale ◽  
Structural Characteristics ◽  
Energy Spectra ◽  
Two Dimensional ◽  
Structural Pattern ◽  
Potential Core ◽  
Planar Jet ◽  
Fluctuation Phase ◽  
Oriented Parallel ◽  
Phase Angles

An experimental study of the developing structural characteristics of a two-dimensional jet in an extremely quiet environment was performed. The jet, at an exit Reynolds number of 6000 and with fluctuation intensity under 0.2% at the mouth, was operated within a large anechoic room. Measurements of energy spectra, fluctuation phase angles and two-dimensionality led to the inference of structural patterns in the flow. These patterns are initially characterized by relatively strong symmetric modes exhibiting limited two-dimensionality and oriented parallel to the mouth of the jet. Subsequent downstream evolution led to the formation of an antisymmetric pattern beyond the jet potential core and the associated development of extended structures possessing a definite large lateral inclination. The results of this work suggest a developing large-scale structural pattern more complicated than previously supposed.

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