The flow past a rectangular cylinder with small cut-corners at the front-edge is investigated to discuss a relation between drag reduction and the cutout dimension. The rectangular shape is selected in eleven kinds of the length-to-breadth ratio from 2/6 to 6/6 (square prism) with the small rectangular-shaped cut-corners at the front-edge. The wind tunnel experiment is carried out to obtain time-averaged hydrodynamic forces measured by the force transducer at $Re≈50,000$. The contour map of the hydrodynamic coefficients with respect to the cutout dimension are shown to investigate the relation between the drag reduction and the cutout shape. In the contour map for the zero angle of attack, the region of the effective drag reduction achieved, in which the value of the drag coefficient is less than that of a circular cylinder at the same Reynolds number, is observed to become wide with the increase in the length-to-breadth ratio and it is independent of the angle of attack, $α$, within $α$ being small. Furthermore, it is shown that there is a condition in which the drag reduction of $CD⪅1.5$ can be achieved even when the Strouhal number is less than 0.2.

1.
Tamura
,
T.
,
Miyagi
,
T.
, and
Kitagishi
,
T.
, 1998, “
Numerical Prediction of Unsteady Pressures on a Square Cylinder With Various Corner Shapes
,”
J. Wind. Eng. Ind. Aerodyn.
0167-6105,
74–76
, pp.
531
542
.
2.
Kurata
,
M.
,
Morisawa
,
T.
,
Hirakawa
,
K.
,
Yasutomi
,
Z.
, and
Kida
,
T.
, 1998, “
Drag Reduction of a Bluff Body With Small Cutout at Its Edges (Case of Prism With Square Cross Section)
,”
JSME Int. J., Ser. B
1340-8054,
64
(
618
), pp.
397
404
.
3.
Kurata
,
M.
,
Hirakawa
,
K.
,
Yasutomi
,
Z.
, and
Kida
,
T.
, 1999, “
Effect of Cutout at Front Edges to Drag Reduction of Square Prism
,”
Trans. Jpn. Soc. Aeronaut. Space Sci.
0549-3811,
47
(
543
), pp.
174
181
.
4.
Kurata
,
M.
,
Hirakawa
,
K.
,
Yasutomi
,
Z.
, and
Kida
,
T.
, 1999, “
Relationship Between Near Wake and Drag Reduction of Square Prism Due to Cutout at Front Edges
,”
Trans. Jpn. Soc. Aeronaut. Space Sci.
0549-3811,
47
(
550
), pp.
403
410
.
5.
Kurata
,
M.
,
Yamato
,
H.
,
Yasutomi
,
Z.
, and
Kida
,
T.
, 2002, “
Effect of Cutout at Edges to Drag Reduction of Square Prism With Angle of Attack
,”
JSME Int. J., Ser. B
1340-8054,
68
(
668
), pp.
1087
1094
.
6.
Igarashi
,
T.
,
Muranaka
,
N.
and
Nakamura
,
H.
, 2005, “
Drag Reduction of a Rectangular Cylinder With Small Rectangular Cutout at Its Edges Normal to Air-Stream
,”
Annual Conference of Japan Society of Fluid Mechanics
, Paper No. AM05-04-016.
7.
Okajima
,
A.
,
Ueno
,
H.
, and
Abe
,
A.
, 1992, “
Influence of Reynolds Number on Flow and Aerodynamics Characteristics of Bluff Bodies With Rectangular Section of Cut Corners
,”
J. Wind. Eng. Ind. Aerodyn.
0167-6105,
49
, pp.
1
13
.
8.
Bearman
,
P. W.
, and
Trueman
,
D. M.
, 1972, “
An Investigation of the Flow Around Rectangular Cylinders
,”
Aeronaut. Q.
0001-9259,
23
, pp.
228
237
.
9.
Igarashi
,
T.
, 1984, “
Characteristics of the Flow Around Rectangular Cylinders (The Case of the Angle of Attack 0 deg)
,”
Trans. Jpn. Soc. Mech. Eng., Ser. B
0387-5016,
50
(
460
), pp.
3185
3192
.
10.
Nakaguchi
,
H.
,
Hashimoto
,
K.
, and
Muto
,
S.
, 1968, “
An Experimental Study on Aerodynamic Drag of Rectangular Cylinders
,”
Trans. Jpn. Soc. Aeronaut. Space Sci.
0549-3811,
16
(
168
), pp.
1
5
.
11.
Ueda
,
Y.
,
Kurata
,
M.
,
Kida
,
T.
, and
Iguchi
,
M.
, 2008, “
Visualization of Flow Past a Square Prism With Cut-Corners at the Front-Edge
,”
J. Visualization
1343-8875, to be published.
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