Suscripción a Biblioteca: Guest
Sixth International Symposium on Turbulence and Shear Flow Phenomena
June, 22-24, 2009 , Seoul National University, Seoul, Korea

DOI: 10.1615/TSFP6

LARGE-EDDY SIMULATION OF A LAMINAR SEPARATION BUBBLE: THE SMAGORINSKY AND DYNAMIC MODELS

pages 569-574
DOI: 10.1615/TSFP6.910
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SINOPSIS

The principal objective of the present simulation is to find the ability of Large-eddy simulation (LES) to resolve the transition mechanism of a laminar separation bubble apart from making a comparative assessment of subgrid-scales (SGS) models. The Smagorinsky model modified by the low-Reynolds number correction of Voke (1996) and the dynamic model are used to account for the non-resolvable subgrid stresses. Two values of the Smagorinsky constant Cs have been tested. Results from the dynamic model are closer to the DNS data compared to those from the Smagorinsky model. The simulation shows that no significant growth of fluctuations is observed in the first 27 percent of bubble length. Three-dimensional motion and non-linear interactions leading to break down to turbulence occur in the second half of the mean bubble length. The simulation also illustrates that the transition process is characterized by break down of longitudinal streaks, which appear via vortex stretching mechanism. The near wall characteristics develop far downstream indicating a very slow relaxation towards an equilibrium turbulent boundary layer.

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