Cross flow past a pair of equal-diameter staggered circular cylinders, with either one of the pair subject to forced harmonic transverse oscillation, is investigated experimentally within Reynolds numbers Re = 525–750. The center-to-center pitch ratio and stagger angle of the cylinders at their mean position are 2.5° and 21°, respectively. Results with cylinder excitation frequencies in the range 0.07 ≤ feD/U ≤ 1.18 (D = cylinder diameter, U = mean flow velocity) at a constant oscillation amplitude (peak-to-peak) of 0.44D are reported. Flow visualization of the wake formation region and hot-film measurements of the wake velocity are reported. Emphasis is placed on the mechanisms leading to vortex shedding. Results show that the wake undergoes considerable modification with the oscillation of either of the two cylinders; this modification depends strongly on the value of feD/U. The flow patterns remain essentially the same as those of the corresponding static cases for feD/U < 0.10. However, the flow at higher oscillation frequencies than that can no longer maintain those patterns. In particular, there are distinct regions of fundamental and superharmonic synchronizations between the dominant wake periodicities and the cylinder oscillation over the whole range of feD/U. Moreover, the manner in which the wake responds to the cylinder oscillation depends strongly on whether it is the upstream or downstream cylinder which is being oscillated.

References

References
1.
Zdravkovich
,
M. M.
, 1987, “
The Effect of Interference Between Circular Cylinders in Cross Flow
,”
J. Fluids Struct.
,
1
, pp.
239
261
.
2.
Gu
,
Z. F.
, and
Sun
,
T. F.
, 1999, “
On Interference Between Two Circular Cylinders in Staggered Arrangement at High Subcritical Reynolds Numbers
,”
J. Wind Eng. Ind. Aerodyn.
,
80
, pp.
287
309
.
3.
Sumner
,
D.
,
Price
,
S. J.
, and
Païdoussis
,
M. P.
, 2000, “
Flow-Pattern Identification for Two Staggered Cylinders in Cross-Flow
,”
J. Fluid Mech.
,
411
, pp.
263
303
.
4.
Koopmann
,
G. H.
, 1967, “
The Vortex Wakes of Vibrating Cylinders at Low Reynolds Numbers
,”
J. Fluid Mech.
,
28
, pp.
501
512
.
5.
Stansby
,
P. K.
, 1976, “
The Locking-of Vortex Shedding due to the Cross-Stream Vibration Circular Cylinders in Uniform and Shear Flows
,”
J. Fluid Mech.
,
74
, pp.
641
655
.
6.
Williamson
,
C. H. K.
, and
Roshko
,
A.
, 1988, “
Vortex Formation in the Wake of an Oscillating Cylinder
,”
J. Fluids Struct.
,
2
, pp.
355
381
.
7.
Ongoren
,
A.
, and
Rockwell
,
D.
, 1988, “
Flow Structure From an Oscillating Cylinder. Part 1. Mechanism of Phase Shift and Recovery in the Near Wake
,”
J. Fluid Mech.
,
191
, pp.
197
223
.
8.
Gu
,
W.
,
Chyu
,
C.
, and
Rockwell
,
D.
, 1994, “
Timing of Vortex Formation From an Oscillating Cylinder
,”
Phys. Fluids
,
6
, pp.
3677
3682
.
9.
Carberry
,
J.
,
Sheridan
,
J.
, and
Rockwell
,
D.
, 2001, “
Forces and Wake Modes of an Oscillating Cylinder
,”
J. Fluids Struct
,
15
, pp.
523
532
.
10.
Feng
,
C. C.
, 1968, “
The Measurement of Vortex-Induced Effects on Flow Past Stationary and Oscillating Circular and D-section Cylinders
,” Master’s Thesis, University of British Colombia, Vancouver, Canada.
11.
Brika
,
D.
, and
Laneville
,
A.
, 1993, “
Vortex-Induced Vibrations of a Long Flexible Cylinder
,”
J. Fluid Mech.
,
250
, pp.
481
508
.
12.
Khalak
,
A.
, and
Williamson
,
C. H. K.
, 1997, “
Fluid Forces and Dynamics of a Hydroelastic Structure With Very Low Mass and Damping
,”
J. Fluids Struct.
,
11
, pp.
973
982
.
13.
Lu
,
X.-Y.
, and
Dalton
,
C.
, 1996, “
Calculation of the Timing of Vortex Formation From an Oscillating Cylinder
,”
J. Fluids Struct.
,
10
, pp.
527
541
.
14.
Blackburn
,
H. M.
, and
Henderson
,
R. D.
, 1999, “
A Study of Two-Dimensional Flow Past an Oscillating Cylinder
,”
J. Fluid Mech.
,
385
, pp.
255
286
.
15.
Mahir
,
N.
, and
Rockwell
,
D.
, 1996, “
Vortex Formation From a Forced System of Two Cylinders. Part I: Tandem Arrangement
,”
J. Fluids Struct.
,
10
, pp.
473
489
.
16.
Mahir
,
N.
, and
Rockwell
,
D.
, 1996, “
Vortex Formation From a Forced System of Two Cylinders. Part II: Side-by-side Arrangement
,”
J. Fluids Struct.
,
10
, pp.
491
500
.
17.
Lai
,
W. C.
,
Zhou
,
Y.
,
So
,
R. M. C.
, and
Wang
,
T.
, 2003, “
Interference Between Stationary and Vibrating Cylinder Wakes
,”
Phys. Fluids
,
15
, pp.
1687
1695
.
18.
Price
,
S. J.
,
Krishnamoorthy
,
S.
, and
Païdoussis
,
M. P.
, 2007, “
Cross-Flow Past a Nearly In-line Cylinders With the Upstream Cylinder Subjected to Transverse Harmonic Oscillation
,”
J. Fluids Struct.
,
23
, pp.
39
57
.
19.
Krishnamoorthy
,
S.
,
Price
,
S. J.
, and
Païdoussis
,
M. P.
, 2001, “
Cross-Flow Past an Oscillating Circular Cylinder: Synchronization Phenomena in the Near Wake
,”
J. Fluids Struct.
,
15
, pp.
955
980
.
20.
Sumner
,
D.
, and
Richards
,
M. D.
, 2003, “
Some Vortex-Shedding Characteristics of the Staggered Configuration of Circular Cylinders
,”
J. Fluids Struct.
,
17
, pp.
345
350
.
21.
Sumner
,
D.
,
Richards
,
M. D.
, and
Akosile
,
O. O.
, 2005, “
Two Staggered Circular Cylinders of Equal Diameter in Cross-Flow
,”
J. Fluids Struct.
,
20
, pp.
255
276
.
22.
Alam
,
M. M.
, and
Sakamoto
,
H.
, 2005, “
Investigation of Strouhal Frequencies of Two Staggered Bluff Bodies and Detection of Multistable Flow by Wavelets
,”
J. Fluids Struct.
,
20
, pp.
425
449
.
23.
Price
,
S. J.
,
Païdoussis
,
M. P.
, and
Krishnamoorthy
,
S.
, 2006, “
Cross-Flow Past a Pair of Staggered Cylinders With the Upstream Cylinder Subjected to Transverse Harmonic Oscillation
,”
Proceeding of ASME Pressure Vessels and Piping Conference/ICPVT-11
,
ASME
, ISBN: 0791837823, paper PVP2006-ICPVT11-93146.
24.
Williamson
,
C. H. K.
, 1985, “
Evolution of a Single Wake Behind a Pair of Bluff Bodies
,”
J. Fluid Mech.
,
159
, pp.
1
18
.
You do not currently have access to this content.