The numerical study reported here deals with the passive flow control around a two-dimensional D-shaped bluff body at a Reynolds number of $Re=3.6×104$. A small circular control cylinder located in the near wake behind the main bluff body is employed as a local disturbance of the shear layer and the wake. 3D simulations are carried out using a newly developed very large eddy simulation (VLES) method, based on the standard k − ε turbulence model. The aim of this study is to validate the performance of this method for the complex flow control problem. Numerical results are compared with available experimental data, including global flow parameters and velocity profiles. Good agreements are observed. Numerical results suggest that the bubble recirculation length is increased by about 36% by the local disturbance of the small cylinder, which compares well to the experimental observations in which the length is increased by about 38%. A drag reduction of about 18% is observed in the VLES simulation, which is quite close to the experimental value of 17.5%. It is found that the VLES method is able to predict the flow control problem quite well.

## References

References
1.
Spalart
,
P.
, and
Mclean
,
J.
,
2011
, “
Drag Reduction: Enticing Turbulence, and Then an Industry
,”
Philos. Trans. R. Soc. London, Ser. A
,
369
, pp.
1556
1569
.10.1098/rsta.2010.0369
2.
Choi
,
H.
,
Jeon
,
W.
, and
Kim
,
J.
,
2008
, “
Control of Flow Over a Bluff Body
,”
Annu. Rev. Fluid Mech.
,
40
, pp.
113
139
.10.1146/annurev.fluid.39.050905.110149
3.
Klumpp
,
S.
,
Meinke
,
M.
, and
Schröder
,
W.
,
2010
, “
Numerical Simulation of Riblet Controlled Spatial Transition in a Zero-Pressure-Gradient Boundary Layer
,”
Flow, Turbul. Combust.
,
85
, pp.
57
71
.10.1007/s10494-010-9251-x
4.
Kuya
,
Y.
,
Takeda
,
K.
,
Zhang
,
X.
,
Beeton
,
S.
, and
Pandaleon.
,
T.
,
2009
, “
Flow Separation Control on a Race Car Wing With Vortex Generators in Ground Effect
,”
ASME J. Fluids Eng.
,
131
, p.
121102
.10.1115/1.4000420
5.
Khalighi
,
B.
,
Chen
,
K.
, and
Iaccarino
,
G.
,
2012
, “
Unsteady Aerodynamic Flow Investigation Around a Simplified Square-Back Road Vehicle With Drag Reduction Devices
,”
ASME J. Fluids Eng.
,
134
, p.
061101
.10.1115/1.4006643
6.
Bruneau
,
C.
,
Mortazavi
,
I.
, and
Gillieron
,
P.
,
2008
, “
Passive Control Around the Two-Dimensional Square Back Ahmed Body Using Porous Devices
,”
ASME J. Fluids Eng.
,
130
, p.
061101
.10.1115/1.2917423
7.
Sreenivasan
,
K.
, and
Strykowski
,
P.
,
1990
, “
On the Formation and Suppression of Vortex Shedding at Low Reynolds Number
,”
J. Fluid Mech.
,
218
, pp.
71
108
.10.1017/S0022112090000933
8.
Dalton
,
C.
,
Xu
,
Y.
, and
Owen
,
J.
,
2001
, “
The Suppression of a Lift on a Circular Cylinder Due to Vortex Shedding at Moderate Reynolds Numbers
,”
J. Fluids Struct.
,
15
, pp.
617
628
.10.1006/jfls.2000.0361
9.
Thiria
,
B.
,
,
O.
, and
Beaudoin
,
J.
,
2009
, “
Passive Drag Control of a Blunt Trailing Edge Cylinder
,”
J. Fluids Struct.
,
25
, pp.
766
776
.10.1016/j.jfluidstructs.2008.07.008
10.
Parezanovic
,
V.
, and
,
O.
,
2012
, “
Experimental Sensitivity Analysis of the Global Properties of a Two-Dimensional Turbulent Wake
,”
J. Fluid Mech.
,
693
, pp.
115
149
.10.1017/jfm.2011.495
11.
Yildirim
,
I.
,
Rindt
,
C.
, and
Steenhoven
,
A.
,
2010
, “
Vortex Dynamics in a Wire-Disturbed Cylinder Wake
,”
Phys. Fluids
,
22
, p.
094101
.10.1063/1.3466659
12.
Mittal
,
S.
,
2001
, “
Control of Flow Past Bluff Bodies Using Rotating Control Cylinders
,”
J. Fluids Struct.
,
15
, pp.
291
326
.10.1006/jfls.2000.0337
13.
Sakamoto
,
H.
, and
Haniu
,
H.
,
1994
, “
Optimum Suppression of Fluid Forces Acting on Circular Cylinder
,”
ASME J. Fluids Eng.
,
116
, pp.
221
227
.10.1115/1.2910258
14.
Parezanovic
,
V.
, and
,
O.
,
2009
, “
The Impact of a Local Perturbation on Global Properties of a Turbulent Wake
,”
Phys. Fluids
,
21
, p.
071701
.10.1063/1.3184615
15.
Krajnović
,
S.
,
2009
, “
LES of Flows Around Ground Vehicles and Other Bluff Bodies
,”
Philos. Trans. R. Soc. London, Ser. A
,
367
, pp.
2917
2930
.10.1098/rsta.2009.0021
16.
Krajnović
,
S.
,
Östh
,
J.
, and
Basara
,
B.
,
2010
, “
LES Study of Breakdown Control of A-Pillar Vortex
,”
Int. J. Flow Control
,
2
, pp.
237
257
.10.1260/1756-8250.2.4.237
17.
Krajnović
,
S.
, and
Fernandes
,
J.
,
2011
, “
Numerical Simulation of the Flow Around a Simplified Vehicle Model With Active Flow Control
,”
Int. J. Heat Fluid Flow
,
32
, pp.
192
200
.10.1016/j.ijheatfluidflow.2010.06.007
18.
Guilmineau
,
E.
,
Deng
,
G.
, and
Wackers
,
J.
,
2011
, “
Numerical Simulation With a DES Approach for Automotive Flows
,”
J. Fluids Struct.
,
27
, pp.
807
816
.10.1016/j.jfluidstructs.2011.03.010
19.
Hemida
,
H.
, and
Krajnović
,
S.
,
2009
, “
Transient Simulation of the Aerodynamics Response of a Double-Deck Bus in Gusty Winds
,”
ASME J. Fluids Eng.
,
131
, p.
031101
.10.1115/1.3054288
20.
Krajnović
,
S.
,
Lárusson
,
R.
, and
Basara
,
B.
,
2012
, “
Superiority of PANS Compared to LES in Predicting a Rudimentary Landing Gear Flow With Affordable Meshes
,”
Int. J. Heat Fluid Flow
,
37
, pp.
109
122
.10.1016/j.ijheatfluidflow.2012.04.013
21.
Han
,
X.
, and
Krajnović
,
S.
,
2013
, “
An Efficient Very Large Eddy Simulation Model for Simulation of Turbulent Flow
,”
Int. J. Numer. Methods Fluids
,
71
, pp.
1341
1360
.10.1002/fld.3714
22.
Han
,
X.
, and
Krajnović
,
S.
, “
Validation of a Novel Very Large Eddy Simulation Method for Simulation of Turbulent Separated Flow
,”
Int. J. Numer. Methods Fluids
(in press).
23.
Sakamoto
,
H.
,
Haniu
,
H.
, and
Tan
,
K.
,
1991
, “
An Optimum Suppression of Fluid Forces by Controlling a Shear Layer Separated From a Square Prism
,”
ASME J. Fluids Eng.
,
113
, pp.
183
189
.10.1115/1.2909478
24.
Giannetti
,
F.
, and
Luchini
,
P.
,
2007
, “
Structural Sensitivity of the First Instability of the Cylinder Wake
,”
J. Fluid Mech.
,
581
, pp.
167
197
.10.1017/S0022112007005654
25.
Speziale
,
C.
,
1998
, “
Turbulence Modeling for Time-Dependent RANS and VLES: A Review
,”
AIAA J.
,
36
, pp.
173
184
.10.2514/2.7499
26.
Fasel
,
H.
,
Seidel
,
J.
, and
Wernz
,
S.
,
2002
, “
A Methodology for Simulations of Complex Turbulent Flows
,”
ASME J. Fluids Eng.
,
124
, pp.
933
942
.10.1115/1.1517569
27.
Sagaut
,
P.
,
Deck
,
S.
, and
Terracol
,
M.
,
2006
,
Multiscale and Multiresolution Approaches in Turbulence
,
Imperial College
,
London
.
28.
Peltier
,
L. J.
, and
Zajaczkowski
,
F. J.
,
2001
, “
Maintenance of the Near-Wall Cycle of Turbulence for Hybrid RANS/LES of Fully-Developed Channel Flow
,”
DNS/LES Progress and Challenges: 3rd AFOSR International Conference
,
C.
Liu
,
T.
Beutner
, and
L.
Sakell
, eds., pp.
829
834
.
29.
Roshko
,
A.
,
1993
, “
Perspectives on Bluff Body Aerodynamics
,”
J. Wind Eng. Ind. Aerodyn.
,
49
, pp.
79
100
.10.1016/0167-6105(93)90007-B