Circular Cylinder Wake Configurations: A Flow Visualization Survey

1991 ◽  
Vol 44 (6) ◽  
pp. 255-305 ◽  
Author(s):  
Madeleine Coutanceau ◽  
Jean-Rene´ Defaye
Keyword(s):  
Circular Cylinder ◽  
High Speed ◽  
Three Dimensional ◽  
Cylinder Wake ◽  
Periodic Motions ◽  
Extended Range ◽  
Different Types ◽  
Speed Regime ◽  
Lock In ◽  
Evolution With Time

The survey starts with the presentation of the general principles underlying the different types of techniques which are most often used in wake visualization with their advantages, but also their respective limits. Then information deduced from flow pictures collected from the literature from the beginning of the century up to the present has been used to characterize the wake structure of a circular cylinder (at rest or submitted to various motions) and its evolution with the Reynolds number for an extended range (0 < Re < 107). Incompressible flow has been more particularly considered, both in the quasi-established phase (ten regimes are differentiated and extensively described) and in the transient phase (specific features are pointed out). Special attention has been paid to three-dimensional and memory effects by a combined presentation of crosswise and spanwise observations of the wake phenomena as well as their evolution with time. The influence of compressibility in the high-speed regime and of superimposed periodic motions, either on the cylinder or on the stream, have been also investigated and the main characteristics of the lock-in regime have been described. The survey is illustrated by 40 figures and completed by a table in which are reported the successive studies related to the flow around a circular cylinder based upon visualization, including a brief account of the experimental setups and methods, as well as a description of the main phenomena observed in the corresponding pictures.

Flow instabilities in the wake of a circular cylinder with parallel dual splitter plates attached

2019 ◽  
Vol 874 ◽  
pp. 299-338 ◽  
Author(s):  
Rui Wang ◽  
Yan Bao ◽  
Dai Zhou ◽  
Hongbo Zhu ◽  
Huan Ping ◽  
...  
Keyword(s):  
Circular Cylinder ◽  
Rear Surface ◽  
Three Dimensional ◽  
Spectral Element ◽  
Cylinder Wake ◽  
Flow Topology ◽  
Weakly Nonlinear ◽  
Plate Length ◽  
Splitter Plates ◽  
Mode A

In this paper, instabilities in the flow over a circular cylinder of diameter $D$ with dual splitter plates attached to its rear surface are numerically investigated using the spectral element method. The key parameters are the splitter plate length $L$, the attachment angle $\unicode[STIX]{x1D6FC}$ and the Reynolds number $Re$. The presence of the plates was found to significantly modify the flow topology, leading to substantial changes in both the primary and secondary instabilities. The results showed that the three instability modes present in the bare circular cylinder wake still exist in the wake of the present configurations and that, in general, the occurrences of modes A and B are delayed, while the onset of mode QP is earlier in the presence of the splitter plates. Furthermore, two new synchronous modes, referred to as mode A$^{\prime }$ and mode B$^{\prime }$, are found to develop in the wake. Mode A$^{\prime }$ is similar to mode A but with a quite long critical wavelength. Mode B$^{\prime }$ shares the same spatio-temporal symmetries as mode B but has a distinct spatial structure. With the exception of the case of $L/D=0.25$, mode A$^{\prime }$ persists for all configurations investigated here and always precedes the transition through mode A. The onset of mode B$^{\prime }$ occurs for $\unicode[STIX]{x1D6FC}>20^{\circ }$ with $L/D=1.0$ and for $L/D>0.5$ with $\unicode[STIX]{x1D6FC}=60^{\circ }$. The characteristics of all the transition modes are analysed, and their similarities and differences are discussed in detail in comparison with the existing modes. In addition, the physical mechanism responsible for the instability mode B$^{\prime }$ is proposed. The weakly nonlinear feature of mode B$^{\prime }$, as well as that of mode A$^{\prime }$, is assessed by employing the Landau model. Finally, selected three-dimensional simulations are performed to confirm the existence of these two new modes and to investigate the nonlinear evolution of the three-dimensional modes.

Radial Deformation Frequency Effect on the Three-Dimensional Flow in the Cylinder Wake

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Mohamed Aissa ◽  
Ahcène Bouabdallah ◽  
Hamid Oualli
Keyword(s):  
Circular Cylinder ◽  
Three Dimensional ◽  
Frequency Effect ◽  
Radial Deformation ◽  
Cylinder Wake ◽  
Near Wake ◽  
Flow Evolution ◽  
Computational Fluid Dynamics Cfd ◽  
Vortex Shedding Frequency ◽  
Forces Behavior

In the current paper, the three-dimensional air flow evolution around a circular cylinder is studied. The main aim is to control the flow field upstream and downstream of a circular cylinder by means of radial deformation. Within a particular step, one focuses on the response of the topological structures, which is developing in the cylinder near wake to applied pulsatile motion. Furthermore, a special care is considered to the aerodynamics forces behavior in adjusting the applied controlling strategy. The used controlling frequency range extends from f = 1fn = 17 Hz to f = 6fn = 102.21 Hz, which corresponds to a series of multiharmonic frequency varying from one to six times the natural vortex shedding frequency (VSF) in none forced wake. Throughout this work, the forcing amplitude is fixed at 16% of cylinder diameter and the Reynolds number as Re = 550. Through Fluent computational fluid dynamics (CFD) code and Matlab simulations, the obtained results showed a good accordance with the calculated ones.

Experimental Study on the Stability of the Flow Behind an Accelerating Circular Cylinder

2007 ◽  
Author(s):  
A. Inasawa ◽  
K. Toda ◽  
M. Asai
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Critical Reynolds Number ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Cylinder Wake ◽  
Global Instability ◽  
The Stability ◽  
Dimensional Instability ◽  
Wake Oscillation

Disturbance growth in the wake of a circular cylinder moving at a constant acceleration is examined experimentally. The cylinder is installed on a carriage moving in the still air. The results show that the critical Reynolds number for the onset of the global instability leading to a self-sustained wake oscillation increases with the magnitude of acceleration, while the Strouhal number of the growing disturbance at the critical Reynolds number is not strongly dependent on the magnitude of acceleration. It is also found that with increasing the acceleration, the Ka´rma´n vortex street remains two-dimensional even at the Reynolds numbers around 200 where the three-dimensional instability occurs to lead to the vortex dislocation in the case of cylinder moving at constant velocity or in the case of cylinder wake in the steady oncoming flow.

Numerical investigation of wake flow regimes behind a high-speed rotating circular cylinder in steady flow

2019 ◽  
Vol 878 ◽  
pp. 875-906
Author(s):  
Adnan Munir ◽  
Ming Zhao ◽  
Helen Wu ◽  
Lin Lu
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Vortex Shedding ◽  
Rotation Rate ◽  
High Speed ◽  
Three Dimensional ◽  
Flow Regimes ◽  
Reynolds Numbers ◽  
Wake Flow ◽  
Rotating Circular Cylinder

Flow around a high-speed rotating circular cylinder for $Re\leqslant 500$ is investigated numerically. The Reynolds number is defined as $UD/\unicode[STIX]{x1D708}$ with $U$, $D$ and $\unicode[STIX]{x1D708}$ being the free-stream flow velocity, the diameter of the cylinder and the kinematic viscosity of the fluid, respectively. The aim of this study is to investigate the effect of a high rotation rate on the wake flow for a range of Reynolds numbers. Simulations are performed for Reynolds numbers of 100, 150, 200, 250 and 500 and a wide range of rotation rates from 1.6 to 6 with an increment of 0.2. Rotation rate is the ratio of the rotational speed of the cylinder surface to the incoming fluid velocity. A systematic study is performed to investigate the effect of rotation rate on the flow transition to different flow regimes. It is found that there is a transition from a two-dimensional vortex shedding mode to no vortex shedding mode when the rotation rate is increased beyond a critical value for Reynolds numbers between 100 and 200. Further increase in rotation rate results in a transition to three-dimensional flow which is characterized by the presence of finger-shaped (FV) vortices that elongate in the wake of the cylinder and very weak ring-shaped vortices (RV) that wrap the surface of the cylinder. The no vortex shedding mode is not observed at Reynolds numbers greater than or equal to 250 since the flow remains three-dimensional. As the rotation rate is increased further, the occurrence frequency and size of the ring-shaped vortices increases and the flow is dominated by RVs. The RVs become bigger in size and the flow becomes chaotic with increasing rotation rate. A detailed analysis of the flow structures shows that the vortices always exist in pairs and the strength of separated shear layers increases with the increase of rotation rate. A map of flow regimes on a plane of Reynolds number and rotation rate is presented.

Simulations of three-dimensional viscoelastic flows past a circular cylinder at moderate Reynolds numbers

2010 ◽  
Vol 651 ◽  
pp. 415-442 ◽  
Author(s):  
DAVID RICHTER ◽  
GIANLUCA IACCARINO ◽  
ERIC S. G. SHAQFEH
Keyword(s):  
Circular Cylinder ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Viscoelastic Flow ◽  
Dimensional Structure ◽  
Recirculation Region ◽  
Viscoelastic Flows ◽  
Cylinder Wake ◽  
Complex Flows

The results from a numerical investigation of inertial viscoelastic flow past a circular cylinder are presented which illustrate the significant effect that dilute concentrations of polymer additives have on complex flows. In particular, effects of polymer extensibility are studied as well as the role of viscoelasticity during three-dimensional cylinder wake transition. Simulations at two distinct Reynolds numbers (Re = 100 and Re = 300) revealed dramatic differences based on the choice of the polymer extensibility (L2 in the FENE-P model), as well as a stabilizing tendency of viscoelasticity. For the Re = 100 case, attention was focused on the effects of increasing polymer extensibility, which included a lengthening of the recirculation region immediately behind the cylinder and a sharp increase in average drag when compared to both the low extensibility and Newtonian cases. For Re = 300, a suppression of the three-dimensional Newtonian mode B instability was observed. This effect is more pronounced for higher polymer extensibilities where all three-dimensional structure is eliminated, and mechanisms for this stabilization are described in the context of roll-up instability inhibition in a viscoelastic shear layer.

Periodic Motions and Bifurcations of a Plastic Impact Machine

2007 ◽  
Vol 340-341 ◽  
pp. 307-312
Author(s):  
Guan Wei Luo ◽  
Yan Long Zhang ◽  
Hui Ming Yao
Keyword(s):  
Mathematical Model ◽  
Three Dimensional ◽  
Periodic Motions ◽  
Impact Machine ◽  
Single Impact ◽  
Synchronous Motion ◽  
Pile Driver ◽  
Characteristic Behavior ◽  
Different Types ◽  
Grazing Contact

A mathematical model is developed to describe the characteristic behavior of a small vibro-impact pile driver. Dynamics of the small vibro-impact pile driver is represented by a three-dimensional map. The map is of piecewise property due to synchronous and non-synchronous motion of the driver and pile immediately after the plastic impact, and singularities caused by grazing contact of the driver and pile. The pile driver exhibits two different types of single-impact periodic motions in different regions of the forcing frequency due to the plastic impacts. Transition of two types of single-impact periodic motions is demonstrated, and the influence of the piecewise property, singularities and various parameters on the performance of the pile driver is analyzed.

Simulations of three dimensional feedback control of a circular cylinder wake

2006 ◽  
Author(s):  
Jurgen Seidel ◽  
Stefan Siegel ◽  
Kelly Cohen ◽  
Volker Becker ◽  
Thomas McLaughlin
Keyword(s):  
Feedback Control ◽  
Circular Cylinder ◽  
Three Dimensional ◽  
Cylinder Wake

Airborne off-target losses and deposition characteristics from a self-propelled, high speed and high clearance ground sprayer

1997 ◽  
Vol 77 (3) ◽  
pp. 493-500 ◽  
Author(s):  
Raj Grover ◽  
John Maybank ◽  
Brian C. Caldwell ◽  
Thomas M. Wolf
Keyword(s):  
High Speed ◽  
Petri Dish ◽  
Field Trials ◽  
Droplet Volume ◽  
Wind Speeds ◽  
Extended Range ◽  
Different Types ◽  
Design Characteristics ◽  
Low Drift ◽  
High Clearance

In order to quantify the drift and deposition characteristics of a self-propelled, high-speed, and high-clearance sprayer, a series of 15 field trials was carried out applying a herbicide:dye mix along a test swath. Three different types of nozzle tips were used, an XR11002 (Extended Range XR Teejet®), and two "low-drift" tips, a DG11002 (Drift Guard Teejet®) and a TT11002 (Turbo Teejet®). On-swath and off-swath deposits were sampled using petri-dish collectors, while the airborne cloud was sampled 5 m downwind of the swath using Rotorod® samplers. In wind speeds of 10 to 31 km h−1, airborne droplet drift was reduced by a factor of two with both "low drift" designs. The differences in the behaviour of the two low-drift tips from the standard tips were attributed to reductions in the total volume emitted as drift-prone droplets by the low-drift tips, resulting from their inherent design characteristics. On-swath deposit uniformity was best with the DG11002 tips and worst with the TT11002 tips, with the XR11002 tips being intermediate. Off-swath-deposits increased with wind speed. Off-swath deposits between 5 and 10 m were proportional to the total airborne mass at 5 m. Key words: Pesticide, Spra-Coupe, droplet drift, flat-fan tips, deposition variability, droplet size, droplet volume

Structural sensitivity of the secondary instability in the wake of a circular cylinder

2010 ◽  
Vol 651 ◽  
pp. 319-337 ◽  
Author(s):  
FLAVIO GIANNETTI ◽  
SIMONE CAMARRI ◽  
PAOLO LUCHINI
Keyword(s):  
Circular Cylinder ◽  
Linear Equations ◽  
Three Dimensional ◽  
Secondary Instability ◽  
Cylinder Wake ◽  
A Posteriori ◽  
Full Agreement ◽  
Structural Perturbation ◽  
The Core ◽  
Mode A

The sensitivity of the three-dimensional secondary instability of a circular-cylinder wake to a structural perturbation of the associated linear equations is investigated. In particular, for a given flow condition, the region of maximum coupling between the velocity components is localized by using the most unstable Floquet mode and its adjoint mode. The variation of this region in time is also found by considering a structural perturbation which is impulsively applied in time at a given phase of the vortex-shedding process. The analysis is carried out for both mode A and mode B types of transition in the wake of a circular cylinder using a finite-difference code. The resulting regions identified as the core of the instability are in full agreement with the results reported in the literature and with the a posteriori checks documented here.

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