Implicit Large Eddy Simulation of Transitional Flows Over Airfoils and Wings

Abstract

The present work aims at predicting the formation of laminar separation bubbles (LSB) and the related transition to turbulence by means of Implicit Large Eddy Simulations with a high-order Discontinuous Galerkin (DG) method. We focus on the ow around an SD7003 rectangular wing section at an angle of attack of 4o degrees and consider two diffierent Reynolds numbers of 10,000 and 60,000 in order to gain insight into the characteristics of the laminar and turbulent regimes. At Reynolds number 10,000 the ow remains laminar and essentially two dimensional over the wing surface, and only the wake appears to exhibit a turbulent behavior. For the case at Reynolds 60,000, the ow is unsteady over the upper wing surface and the time averaged streamlines show a separation bubble which starts at about 24% of the chord. A close to 51% of the chord, the ow is fully turbulent. These findings appear to be in agreement with previously published results despite the relatively coarse meshes employed, which suggest that the DG method used is particularly suited to simulate these flows. Finally, transition is found to be caused by unstable Tollmien- Schlichting (TS) waves, as revealed by the growth of the stream-wise amplification factor.