Steady-state Reynolds-averaged Navier-Stokes (RANS) simulations are presented for the three-dimensional flow over a simplified tractor/trailer geometry at zero degrees yaw angle. The simulations are conducted using a multi-block, structured computational fluid dynamics (CFD) code. The turbulence closure model employed is the two-equation Menter k-ω model. The discretization error is estimated by employing two grid levels: a fine mesh of 20 million cells and a coarser mesh of 2.5 million cells. Simulation results are compared to experimental data obtained at the NASA-Ames 7×10ft wind tunnel. Quantities compared include vehicle drag, surface pressures, and time-averaged velocities in the trailer near wake. The results indicate that the RANS approach is able to accurately predict the surface pressure on the vehicle, with the exception of the base region. The pressure predictions in the base region are poor due to the inability of the RANS model to accurately capture the near-wake vortical structure. However, the gross pressure levels in the base region are in reasonable agreement with experiment, and thus the overall vehicle drag is well predicted.

1.
McCallen
,
R.
,
Couch
,
R.
,
Hsu
,
J.
,
Browand
,
F.
,
Hammache
,
M.
,
Leonard
,
A.
,
Brady
,
M.
,
Salari
,
K.
,
Rutledge
,
W.
,
Ross
,
J.
,
Storms
,
B.
,
Heineck
,
J. T.
,
Driver
,
D.
,
Bell
,
J.
, and
Zilliac
,
G.
, 1999, “
Progress in Reducing Aerodynamic Drag for Higher Efficiency of Heavy Duty Trucks (Class 7-8)
,” SAE Paper No. 1999-01-2238.
2.
Wilcox
,
D. C.
, 1998,
Turbulence Modeling for CFD
,
2nd ed.
,
DCW Industries, Inc.
,
La Canada, CA
.
3.
Roy
,
C. J.
,
DeChant
,
L. J.
,
Payne
,
J. L.
, and
Blottner
,
F. G.
, 2003, “
Bluff-Body Flow Simulations Using Hybrid RANS/LES
,” AIAA Paper No. 2003-3889.
4.
Iaccarino
,
G.
,
Ooi
,
A.
,
Durbin
,
P. A.
, and
Behnia
,
M.
, 2003, “
Reynolds Averaged Simulation of Unsteady Separated Flow
,”
Int. J. Heat Fluid Flow
0142-727X,
24
, pp.
147
156
.
5.
Rodi
,
W.
, 1997, “
Comparison of LES and RANS Calculations of the Flow Around Bluff Bodies
,”
J. Wind. Eng. Ind. Aerodyn.
0167-6105,
69–71
, pp.
55
75
.
6.
Roy
,
C. J.
,
Payne
,
J. L.
,
McWherter-Payne
,
M. A.
, and
Salari
,
K.
, 2004, “
RANS Simulations of a Simplified Tractor/Trailer Geometry
,”
Lecture Notes in Applied and Computational Mechanics, Vol. 19: The Aerodynamics of Heavy Vehicles: Trucks, Buses, and Trains
,
R.
McCallen
,
F.
Browand
, and
J.
Ross
, Eds.,
Springer
,
Berlin, Germany
, pp.
207
218
.
7.
Salari
,
K.
,
Ortega
,
J. M.
, and
Castellucci
,
P. J.
, 2004, “
Computational Prediction of Aerodynamic Forces for a Simplified Integrated Tractor-Trailer Geometry
,” AIAA Paper No. 2004-2253.
8.
Cooper
,
K. R.
, 2003, “
Truck Aerodynamics Reborn—Lessons from the Past
,” SAE Paper No. 2003-01-3376.
9.
Storms
,
B. L.
,
Ross
,
J. C.
,
Heineck
,
J. T.
,
Walker
,
S. M.
,
Driver
,
D. M.
, and
Zilliac
,
G. G.
, 2001, “
An Experimental Study of the Ground Transportation System (GTS) Model in the NASA Ames 7-by 10-ft Wind Tunnel
,” NASA TM-2001-209621.
10.
Wong
,
C. C.
,
Soetrisno
,
M.
,
Blottner
,
F. G.
,
Imlay
,
S. T.
, and
Payne
,
J. L.
, 1995, “
PINCA: a Scalable Parallel Program for Compressible Gas Dynamics With Nonequilibrium Chemistry
,” Sandia National Laboratories Report SAND 94-2436, Albuquerque, NM.
11.
Yee
,
H. C.
, 1987, “
Implicit and Symmetric Shock Capturing Schemes
,” NASA-TM-89464.
12.
Roe
,
P. L.
, 1981, “
Approximate Riemann Solvers, Parameter Vectors, and Difference Schemes
,”
J. Comput. Phys.
0021-9991,
43
, pp.
357
372
.
13.
Yoon
,
S.
, and
Jameson
,
A.
, 1988, “
An LU-SSOR Scheme for the Euler and Navier-Stokes Equations
,” AIAA Paper No. 87-0600.
14.
Roy
,
C. J.
,
McWherter-Payne
,
M. A.
, and
Oberkampf
,
W. L.
, 2003, “
Verification and Validation for Laminar Hypersonic Flowfields Part 1: Verification
,”
AIAA J.
0001-1452,
41
(
10
), pp.
1934
1943
.
15.
Menter
,
F. R.
, 1994, “
Two-Equation Eddy-Viscosity Turbulence Models for Engineering Applications
,”
AIAA J.
0001-1452,
32
, pp.
1598
1605
.
16.
Roy
,
C. J.
, and
Blottner
,
F. G.
, 2003, “
Methodology for Turbulence Model Validation: Application to Hypersonic Transitional Flows
,”
J. Spacecr. Rockets
0022-4650,
40
(
3
), pp.
313
325
.
17.
Spalart
,
P. R.
, and
Allmaras
,
S. R.
, 1994, “
A One-Equation Turbulence Model for Aerodynamic Flows
,”
Rech. Aerosp.
0034-1223,
1
, pp.
5
21
.
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