Abonnement à la biblothèque: Guest
Fourth International Symposium on Turbulence and Shear Flow Phenomena
June, 27-29, 2005, Marriot Hotel, Williamsburg, Virginia, USA

DOI: 10.1615/TSFP4

COMPUTATIONAL ANALYSIS OF LOCALLY FORCED FLOW OVER A WALL-MOUNTED HUMP AT HIGH-RE NUMBER

pages 1189-1194
DOI: 10.1615/TSFP4.1980
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RÉSUMÉ

An incompressible, high-Reynolds number flow (slightly less then 1 Mio. per chord) over a smoothly contoured wall-mounted hump was studied computationally by using the LES (Large Eddy Simulation) and DES (Detached Eddy Simulation) methods. In addition the Spalart−Allmaras model within the RANS (Reynolds-Averaged Navier-Stokes) framework was tested. The focus of the investigation was on the effects of the local perturbation of the hump boundary layer introduced by the spatially uniform (in the spanwise direction) steady suction and oscillatory suction/blowing through a narrow opening (4mm) situated at the hump crest immediately upstream of the natural separation point. Reference experiments have shown that both flow control mechanisms cause a shortening of the recirculation bubble relative to the baseline configuration (no flow control). The LES method, despite the coarse mesh (with a total of 4 Mio. cells) for this high Reynolds number, wall-bounded flow, was capable of capturing important effects of the flow control qualitatively and quantitatively, whereas DES failed to do so, inspite of superior results in the baseline case. A sensitivity study of the RANS-LES interface position within the DES approach shows that a RANS region chosen too thin (with the interface situated at the very beginning of the logarithmic layer) can lead to a strong reduction of the turbulent viscosity causing a low turbulence level within the shear layer region aligned with the recirculation zone, which in turn leads to a larger separation bubble.

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