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Sixth International Symposium on Turbulence and Shear Flow Phenomena
June, 22-24, 2009 , Seoul National University, Seoul, Korea

DOI: 10.1615/TSFP6

LES OF FLOW PAST CIRCULAR AND ELLIPTIC CYLINDERS IN PROXIMITY TO A WALL

pages 1231-1236
DOI: 10.1615/TSFP6.1960
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SINOPSIS

Flow past a circular (axis ratio, AR = 1) and elliptical cylinders of different AR (AR = 2, 3, 4) in the vicinity of a wall have been investigated for a constant gap-to-diameter ratio, G/D = 0.5 (where, G signifies the gap between the cylinder and flat plate and D the elliptic cylinder minor diameter). Large-eddy simulations (LES) have been carried out with the dynamic subgrid model for a Reynolds number, Re = 1440 (based on D and free-stream velocity U). Simulations have also been performed for three different G/D ratios of 0.25, 0.5 and 1.0 following the experiment of Price et al. [2002], where a circular cylinder was used. The unsteady, three-dimensional Navier-Stokes equations have been solved on a staggered mesh arrangement using a symmetry-preserving central difference scheme, which is widely used in LES owing to its non-dissipative and conservative property. The immersed boundary (IB) method is employed to impose the no-slip boundary condition on the cylinder surface. An attempt is made to understand the physics of flow involving interactions of shear layers shed from the cylinder and the wall boundary layer. Present LES reveals the shear layer instability and formation of smallscale eddies apart from their mutual interactions with the boundary layer. It has been observed that both the shape of the cylinder and the G/D ratio have a strong influence on the modification of wake dynamics and evolution of the wall boundary layer.

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