Numerical study on the three-dimensional unsteady flow past a 5:1 rectangular cylinder using the DES approach

This paper deals with the numerical Detached-Eddy Simulation (DES) of the unsteady flow past a sta-tionary two-dimensional rectangular cylinder with chord-to-thickness ratio B/D = 5.0, at low Mach number (M∞ = 0.1), relatively high Reynolds number (Re = 26,400 based on the body thickness D) and zero flow incidence (α = 0°). This geometry has often been assumed as a reference test case for studies dealing with bridge aerodynamics and aeroelasticity and, despite the simple geometry, it presents inter-esting and complex flow features. For these reasons it was chosen for the benchmark study BARC (Bartoli et al., 2008; Bruno et al., 2010; Mannini et al., 2010a,b). In this work particular attention was devoted to the choice of the more appropriate algorithm to discretize the inviscid fluxes of the governing equations, in view of the numerical dissipation intro-duced in the solution. In addition, the effect of the spanwise extension of the computational domain was investigated. A detailed analysis of the flow results obtained will also be given.