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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

SGS MODELLING IN LES OF WALL-BOUNDED FLOWS USING TRANSPORT RANS MODELS: FROM A ZONAL TO A SEAMLESS HYBRID LES/RANS METHOD

pages 1057-1062
DOI: 10.1615/TSFP6.1680
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RESUMO

Employment of an advanced, Reynolds-stress anisotropy-accounting RANS (Reynolds-Averaged Navier- Stokes) model in the hybrid RANS/LES (Large Eddy Simulation) framework was investigated in the present work. The model in question is the four-equation, near-wall elliptic-relaxation eddy-viscosity model, solving the transport equations for ζ = ν2 / k (with ν2 representing a scalar variable reducing to the normal-to-the-wall Reynolds stress component by approaching the solid wall) and a corresponding elliptic function f in addition to the k and ε- equations. This model, proposed by Hanjalic et al. (2004), is employed in both hybrid LES/RANS strategies tackled in the present work: a zonal and a seamless one. In the former method the k-ε-ζ-f model resolving the near-wall region is bridged at a discrete, dynamically determined interface with the conventional LES covering the outer layer (flow core). In the framework of the seamless method the k-ε-ζ-f model mimics a subgrid-scale (SGS) model in the entire flow domain in line with the PITM (Partially-Integrated Transport Model) procedure proposed by Chaouat and Schiestel (2005, 2007). The feasibility of both computational schemes is assessed in the flow over periodically arranged hills (Frohlich et al., 2005; Breuer, 2005) featuring flow separation from a continuous curved surface. The results obtained by both hybrid LES/RANS methods exhibit reasonable agreement with reference database especially in the separated shear layer region contrary to their RANS counterpart.

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