The near-wake flow of a simplified 3D fastback vehicle is studied according to a numerical approach based on the original LBM. The results obtained concur with the experimental and numerical results found in the literature and the various longitudinal and transversal separated vortices forming the wake are correctly reproduced. The results show the formation of a separated layer on the rear window. The velocity profiles measured in the median longitudinal plane of the geometry indicate that the flow separates at the end of the roof and reattaches itself at the bottom of the rear window. These profiles effectively concur with the profiles measured experimentally in the reference works. The friction line field also reveals a strong interaction between the separated region and the longitudinal vortices, which feed the parietal fluid recirculation under the separated layer. The topology of the longitudinal vortices is also analyzed. The axial and azimutal velocity profiles measured in the vortex core indicate a swirling jet structure, in accordance with the results found in the literature. After a formation phase on the top of the rear window, the longitudinal vortex structure appears in a columnar state along the side edge. The results herein and the comparisons conducted with the experimental results constitute a validation of the computation code for the representation of bluff body near-wake flow characteristic of automotive vehicle wake. The numerical simulation presented can therefore be used to develop and parametrize active control solutions with a view to improve the aerodynamic performances of automobile vehicles. In this context, the topological results presented can be used to determine the control objectives: A reduction of aerodynamic drag consists therefore in finding solutions capable of limiting (even eliminating) the development of the longitudinal vortices and the separated layer development on the rear window.
Separated flows around the rear window of a simplified car geometry
Abgelöste Strömungen am Heckfenster einer vereinfachten Fahrzeuggeometrie
Transactions of the ASME, Series I. Journal of Fluids Engineering ; 130 , 2 ; 021101/1-021101/10
2008
10 Seiten, 12 Bilder, 1 Tabelle, 34 Quellen
Article (Journal)
English
Numerical study of separated flow around rear of road vehicle
Automotive engineering | 2000
|Plastics rear window having rear window heater and method for producing plastics rear window
European Patent Office | 2016
|Separated Flows Around Spoilers and Forward-Facing Flaps
AIAA | 1998
|