Effect of rotating control cylinder location on vortex shedding behind a main cylinder

2020 ◽  
Author(s):  
Deepakkumar R ◽  
Jayavel S
Keyword(s):  
Vortex Shedding ◽  
Control Cylinder

Suppression of vortex shedding behind a circular cylinder by another control cylinder at low Reynolds numbers

2007 ◽  
Vol 573 ◽  
pp. 171-190 ◽  
Author(s):  
A. DIPANKAR ◽  
T. K. SENGUPTA ◽  
S. B. TALLA
Keyword(s):  
Vortex Shedding ◽  
Physical Mechanism ◽  
Grid Method ◽  
Reynolds Numbers ◽  
Accurate Solution ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Low Reynolds Numbers ◽  
Low Reynolds ◽  
Control Cylinder

Vortex shedding behind a cylinder can be controlled by placing another small cylinder behind it, at low Reynolds numbers. This has been demonstrated experimentally by Strykowski & Sreenivasan (J. Fluid Mech. vol. 218, 1990, p. 74). These authors also provided preliminary numerical results, modelling the control cylinder by the innovative application of boundary conditions on some selective nodes. There are no other computational and theoretical studies that have explored the physical mechanism. In the present work, using an over-set grid method, we report and verify numerically the experimental results for flow past a pair of cylinders. Apart from providing an accurate solution of the Navier–Stokes equation, we also employ an energy-based receptivity analysis method to discuss some aspects of the physical mechanism behind vortex shedding and its control. These results are compared with the flow picture developed using a dynamical system approach based on the proper orthogonal decomposition (POD) technique.

Vortex Shedding with Fluid Mechanics from Two Cylinders of Different Diameters in a Tandem Arrangement

2014 ◽  
Vol 886 ◽  
pp. 436-439
Author(s):  
Yong Tao Wang ◽  
Zhong Min Yan ◽  
Hui Min Wang
Keyword(s):  
Reynolds Number ◽  
Fluid Mechanics ◽  
Vortex Shedding ◽  
Diameter Ratio ◽  
Circular Cylinders ◽  
Tandem Arrangement ◽  
Gap Ratio ◽  
Different Diameters ◽  
Upstream Control ◽  
Control Cylinder

The vortex shedding from two circular cylinders of different diameters in a tandem arrangement is numerically investigated at a Reynolds number of 100 and 150. The studied Reynolds number based on the diameter of the downstream main cylinder. The diameter of the downstream main cylinder was kept constant, and the diameter ratio between the upstream control cylinder and the downstream one was varied from 0.1 to 1.0. The gap between the control cylinder and the main cylinder ranged from 0.1 to 4.0 times the diameter of the main cylinder. It is concluded that the gap ratio and the diameter ratio between the two cylinders have important effects on vortex shedding from two cylinders of different diameters in a tandem arrangement.

Numerical Study of Flow Patterns in a Tandem Array Cylinder System

2015 ◽  
Vol 07 (03) ◽  
pp. 1550034 ◽  
Author(s):  
Li-Chieh Hsu ◽  
Jian-Zhi Ye
Keyword(s):  
Vortex Shedding ◽  
Spectral Element Method ◽  
Numerical Study ◽  
Numerical Technique ◽  
Spectral Element ◽  
Flow Patterns ◽  
Critical Distance ◽  
Tandem Array ◽  
Bistable Regime ◽  
Control Cylinder

The spectral element method, a direct numerical technique, is used to study the behavior of flow past two cylinders in tandem array. A control cylinder is employed in front of the main cylinder to study the drag reduction performance and flow patterns. Three major flow patterns are found, including single cylinder vortex shedding, two cylinders vortex shedding and suppression. The flow patterns are affected by the distance between two cylinders, Reynolds number and the diameter ratios of cylinders. In a bistable regime, when there is a critical distance between cylinders, drag is reduced dramatically.

Optimum Suppression of Fluid Forces Acting on a Circular Cylinder

1994 ◽  
Vol 116 (2) ◽  
pp. 221-227 ◽  
Author(s):  
H. Sakamoto ◽  
H. Haniu
Keyword(s):  
Circular Cylinder ◽  
Flow Control ◽  
Flow Pattern ◽  
Vortex Shedding ◽  
Fluid Forces ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency ◽  
Unsteady Fluid ◽  
And Control ◽  
Control Cylinder

The objective of this paper is to investigate the suppression of the fluid forces acting on a circular cylinder (hereafter called the main cylinder) by controlling the flow around it. Flow control was established by introducing a fine circular cylinder (hereafter called the control cylinder) near the main cylinder. Measurements were carried out with variation of the position of the control cylinder in the ranges of G/d = 0.004 ~ 0.20 (G is the gap between main cylinder and control cylinder, d is diameter of main cylinder) and α = 0 ~ 180 deg (α is the angle along circumference from the front stagnation point of main cylinder) at a Reynolds number of 6.5 × 104. Subsequently, the steady and unsteady fluid forces, vortex shedding frequency and flow pattern were systematically examined. Furthermore, such matters as the mechanism of the flow control, the nature of the controlled wake, the relationship between the characteristics of the controlled fluid forces, and the behavior of the flow were discussed in detail on the basis of the obtained results regarding fluid forces, vortex shedding frequency and flow pattern.

Suppression of Vortex Shedding With Rotating Wake-Control Cylinders: Numerical Investigation at a Moderate Reynolds Number

2018 ◽  
Author(s):  
Gustavo R. S. Assi ◽  
Reinaldo M. Orselli ◽  
Mariana Silva-Ortega
Keyword(s):  
Reynolds Number ◽  
Vortex Shedding ◽  
Three Dimensional ◽  
Physical Mechanisms ◽  
Moderate Reynolds Number ◽  
Consequent Reduction ◽  
Flow Induced Vibrations ◽  
The Mean ◽  
Control Cylinder ◽  
Vortex Tubes

This paper presents an investigation of the suppression of vortex shedding of a larger circular cylinder by the interference of smaller rotating wake-control cylinders positioned around its center. Three-dimensional numerical simulations have been conducted at a moderate Reynolds number of 10,000, thus complementing the previous experimental results by offering a better understanding of the physical mechanisms behind the suppression. Visualization of the vortex wakes revealed a complex disruption of the vortex tubes for the higher rotation speeds, with consequent reduction in the mean drag of almost 52% when compared with that of a bare cylinder. Fluctuating lift has also been drastically reduced in 90%. Configurations of control cylinder that can suppress vortex shedding may produce more efficient suppressors for flow-induced vibrations.

Influence of control cylinder placement on vortex shedding from a circular cylinder

2018 ◽  
Vol 59 (10) ◽  
Author(s):  
Conrad Bingham ◽  
Chris Morton ◽  
Robert J. Martinuzzi
Keyword(s):  
Circular Cylinder ◽  
Vortex Shedding ◽  
Control Cylinder

Suppression of Vortex Shedding of Circular Cylinder by a Small Control Rod

2013 ◽  
Vol 477-478 ◽  
pp. 265-270 ◽  
Author(s):  
Li-Chieh Hsu ◽  
De-Chang Lai ◽  
Jian-Zhi Ye
Keyword(s):  
Vortex Shedding ◽  
Reynolds Numbers ◽  
Flow Patterns ◽  
Near Wake ◽  
Control Rod ◽  
Low Reynolds Numbers ◽  
Numerical Studies ◽  
Vortex Shedding Frequency ◽  
Physical Phenomena ◽  
Control Cylinder

The physical phenomena of vortex suppression and flow patterns by deploying a very mall control cylinder in the near wake region of a main cylinder in low Reynolds numbers is studied numerically. The control diameter effect on vortex suppression and three flow patterns has been studied. The results shows the control cylinder can reduce vortex shedding frequency and suppress shedding partially or completely dependent on the diameter of control cylinder and Reynolds number. The results of a cylinder with control and without control agree with experimental and numerical studies.

An Optimum Suppression of Fluid Forces by Controlling a Shear Layer Separated From a Square Prism

1991 ◽  
Vol 113 (2) ◽  
pp. 183-189 ◽  
Author(s):  
H. Sakamoto ◽  
K. Tan ◽  
H. Haniu
Keyword(s):  
Shear Layer ◽  
Vortex Shedding ◽  
Outer Boundary ◽  
Fluid Forces ◽  
Separated Shear Layer ◽  
Square Prism ◽  
Thin Region ◽  
Vortex Shedding Frequency ◽  
Lift And Drag ◽  
Control Cylinder

This paper deals with the suppression of the fluid forces by controlling a shear layer on one side separated from a square prism. The control of the separated shear layer was established by setting up a small circular cylinder (the control cylinder) in it on one side. Experimental data were collected to examine the effects on the fluid forces and vortex shedding frequency due to variation of the position and diameter of the control cylinder. The results show that (i) the maximum reduction of the time-mean drag and fluctuating lift and drag occurred when the control cylinder was located near what would ordinarily be considered the outer boundary of the shear layer; (ii) the control of the separated shear layer by means of a small cylinder appeared to be effective in suppressing the fluctuating lift and drag rather than the time-mean drag; (iii) in the case of the control cylinder of 6 mm in diameter, the time-mean drag was reduced to about 30 percent, and the fluctuating lift and drag were reduced to approximately 95 and 75 percent, respectively; (iv) the fluid forces and the frequency of vortex shedding of the square prism were mainly dependent on the characteristics of a very thin region near the outer boundary of the shear layer.

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