LES of turbulent flow past a swept fence

Abstract

The present study deals with the large-eddy simulation of the span-wise invariant turbulent flow past a swept fence at low Reynolds numbers. The swept fence geometry was introduced by McCluskey et al. [Eighth Symposium on Turbulent Shear Flows, 1991, p. 9.5.1] as a way of gathering information on the behaviour of near wall flows beneath a separation region in the presence of a significant cross flow. The configuration avoids both the lack of generality of typical statistically two-dimensional flows and the difficulties of fully three-dimensional flows. In the present case, large-eddy simulation is both a challenging and promising approach. On the one hand, as in most low-Reynolds number and recirculating flows, simple wall models cannot be applied [Engineering Turbulence Modelling and Experiments 2, Florence, Italy, p. 303] on the other hand, due to the relatively low Reynolds of the flow and the type of scaling suggested in Hardman and Hancock [Exp. Fluids 27 (2000) 653], accurate resolution of the near wall region can be achieved without incurring prohibitively high computational costs. A variant of the dynamic SGS model of Germano et al. [Phys. Fluids A 3 (1991) 1760] with a smooth and reliable numerical behaviour is also tested in this flow. The agreement with the experimental data of Hardman [Moderately three-dimensional separated and reattaching turbulent flow. Ph.D. thesis, University of Surrey, 1998] is found to be satisfactory.