scholarly journals Characteristics of Flow over two Tandem Cylinders of Different Diameters

2015 ◽  
Author(s):  
Yongtao Wang
Keyword(s):  
Tandem Cylinders ◽  
Different Diameters

Interference Between Two Tandem Cylinders of Different Diameters

2006 ◽  
Author(s):  
Md. Mahbub Alam ◽  
Y. Zhou
Keyword(s):  
Low Frequency ◽  
Shear Layers ◽  
Diameter Ratio ◽  
The Other ◽  
Flow Structures ◽  
Incident Flow ◽  
Tandem Cylinders ◽  
Cylinder Diameter ◽  
Different Diameters ◽  
Dominant Frequencies

This paper presents a detailed investigation of Strouhal frequencies, forces and flow structures resulting from the interference between two tandem cylinders of different diameters. The upstream cylinder diameter (d) was varied from 25 mm to 6 mm, while the downstream cylinder diameter (D) of 25 mm was unchanged, the corresponding diameter ratio, d/D, being 1.0 ∼ 0.24. The spacing between the cylinders was 5.5d. At this spacing, the shear layers separated from the upstream cylinder roll up alternately, forming a vortex street in the gap between and behind the cylinders. Two dominant frequencies are detected behind the downstream cylinder at d/D = 1.0 ∼ 0.4. One is the same as detected between the cylinders, and the other is of relatively low frequency and is probably generated by the downstream cylinder. Whilst the former remains unchanged, the latter increases with decreasing d/D, due to an increase in the incident flow velocity of the downstream cylinder. The time-averaged drag on the downstream cylinder also increases with decreasing d/D, though the fluctuating forces drop because vortices impinging upon the downstream cylinder are impaired by decreasing d/D.

Lift Coefficients and Pressure Distribution Acting on Two Tandem Cylinders of Different Diameters

2014 ◽  
Vol 886 ◽  
pp. 417-421
Author(s):  
Yong Tao Wang ◽  
Zhong Min Yan ◽  
Hui Min Wang
Keyword(s):  
Reynolds Number ◽  
Pressure Distribution ◽  
Flow Characteristics ◽  
Diameter Ratio ◽  
Tandem Arrangement ◽  
Tandem Cylinders ◽  
Gap Ratio ◽  
Different Diameters ◽  
Upstream Control ◽  
Control Cylinder

Flow characteristics of two different diameters cylinders in a tandem arrangement were investigated numerically in a uniform flow. 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 studied Reynolds number based on the diameter of the downstream main cylinder were 100 and 150. 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 the lift coefficients and pressure distribution.

Numerical Simulation of Vortex-Induced Vibration of Two Tandem Cylinders With Different Diameters Under Uniform Flow

2020 ◽  
Author(s):  
Xuepeng Fu ◽  
Yuwang Xu ◽  
Mengmeng Zhang ◽  
Haojie Ren ◽  
Bing Zhao ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Experimental Study ◽  
Stokes Equations ◽  
Circular Cylinders ◽  
Navier Stokes ◽  
Flexible Cylinder ◽  
Single Cylinder ◽  
Frequency Capture ◽  
Tandem Cylinders ◽  
Different Diameters

Abstract Vortex-induced vibrations (VIV) of two elastically mounted circular cylinders with different diameters in tandem arrangement are investigated in a two-dimensional (2D) numerical simulation. The fluid domain is simulated by solving 2D Reynold-Averaged Navier-Stokes equations. Meanwhile, the VIV response of the structures is obtained by solving the motion equation using the 4th Runge-Kutta method. The parameters of the cylinders are designed according to an experimental study of flexible risers. Simulation of an elastically mounted single cylinder is firstly carried out and compared with published experimental results to verify the method utilized in the paper. The results of single cylinder show the response frequencies of the bluff cylinders and the flexible cylinder are comparable. In the simulation of the tandem cylinders, a “frequency capture” phenomenon that the oscillation frequencies of downstream cylinder are locked on to that of the up-stream one although they are with different diameters is observed. It also occurs in the experimental study of flexible cylinders. The mechanism behind is analyzed in the paper.

Drag Coefficients Acting on Two Tandem Cylinders of Different Diameters

2014 ◽  
Vol 886 ◽  
pp. 413-416
Author(s):  
Yong Tao Wang ◽  
Zhong Min Yan ◽  
Hui Min Wang
Keyword(s):  
Flow Characteristics ◽  
Diameter Ratio ◽  
Circular Cylinders ◽  
Drag Coefficients ◽  
Tandem Cylinders ◽  
Gap Ratio ◽  
Different Diameters ◽  
Volume Method ◽  
Upstream Control ◽  
Control Cylinder

The flow past two tandem circular cylinders of different diameters is simulated by using a finite volume method. The diameter of the downstream main cylinder is kept constant, and the diameter ratio between the upstream control cylinder and the downstream one is varied from 0.1 to 1.0. The Reynolds number based on the diameter of the downstream main cylinder is 100 and 150. The gap between the control cylinder and the main cylinder ranges 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 the drag coefficients and flow characteristics.

Two tandem cylinders of different diameters in cross-flow: flow-induced vibration

2017 ◽  
Vol 829 ◽  
pp. 621-658 ◽  
Author(s):  
Bin Qin ◽  
Md. Mahbub Alam ◽  
Yu Zhou
Keyword(s):  
Particle Image ◽  
Cross Flow ◽  
Careful Examination ◽  
Laser Vibrometer ◽  
Flow Induced Vibration ◽  
Frequency Responses ◽  
Tandem Cylinders ◽  
Image Velocimetry ◽  
Different Diameters ◽  
Fixed Cylinder

This paper presents a systematic study of the cross-flow-induced vibration on a spring-supported circular cylinder of diameter $D$ placed in the wake of a fixed cylinder of smaller diameter $d$. The ratios $d/D$ and $L/d$ are varied from 0.2 to 1.0 and from 1.0 to 5.5, respectively, where $L$ is the distance between the centre of the upstream cylinder to the forward stagnation point of the downstream cylinder. Extensive measurements are conducted to capture the cylinder vibration and frequency responses, surface pressure, shedding frequencies and flow fields using laser vibrometer, hot-wire, pressure scanner and particle image velocimetry techniques. Six distinct flow regimes are identified. It has been found that a violent vibration may erupt for the spring-supported cylinder, and its dependence on $d/D$ and $L/d$ is documented. A careful examination and analysis of the flow structure, along with the simultaneously captured pressure distribution around and vibration of the downstream cylinder, cast light upon the mechanisms behind this vibration and its sustainability. The roles of added mass, flow-induced damping and physical aspects in the process of initiating the vibration are discussed in detail.

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