5 Computational Visualization of Unsteady Flow Around Vehicles
Using High Performance Computing5.1 LES5.2 LESCFD5.3 LES5.4
5.1 LES Makoto Tsubokura , Toshio Kobayashi, Takuji Nakashima,
Takahide Nouzawa , Takaki Nakamura ,Huilai Zhang , Keiji Onishi,
Nobuyuki Oshima 20085ELSEVIERComputational Visualization of
Unsteady Flow Around Vehicles Using High Performance
ComputingLES
5.1 LESCFD Computational Fluid Dynamics has two fundamental
problems : its strong dependence on turbulence models adopted, and
its difculty of capturing the unsteady ow characteristics. Thus,
RANS plays only a supplementary role of a wind tunnel test at the
moment.CFDRANS(the Reynolds-Averaged NavierStokes model)
5.1 LESLES Large Eddy Simulation LES Large Eddy Simulation will
be an encouraging solution to the problem because it can reproduce
unsteady turbulence characteristics with high accuracy, but in turn
it requires excessively large computational resources.
Consequently, only few attempts have been made so far to apply LES
to the assessment of vehicle aerodynamics.
5.1 LES RSSHPC-LES(High Performance Computing Large Eddy
Simulation )AMSO
5.2 LESCFDAtenza1:1
5.1
5.2 LESCFD 38007005.2 5.3
5.2 LESCFD CFDLESLES5.4
5.3 LES5.5 LES
5.3 LES5.6
5.4 5.7
5.4 5.8 0.10.15S
5.4 5.9 0.20.25S 0 -5 0.15s0.2s0
5.4 0.15s 0.2s This result clearly indicates the fact that,
compared with the situation when the yaw-angle is stationary, a
relatively strong yawing moment acts on the car during the dynamic
yaw-angle change. The figure also explains that, comparing those at
T = 0.15 s and 0.2 s, the main reason of the unsteady yawing moment
is the negative pressure on the rear of the body.
