Numerical investigation on the three-dimensional unsteady flow past a 5:1 rectangular cylinder

This paper deals with the three-dimensional simulation of the unsteady flow around a stationary 5:1 rectangular cylinder at zero-degree angle of attack, low Mach number (M_∞=0.1) and high Reynolds number (Re=26,400, based on the plate thickness). Detached-Eddy Simulation (DES) was adopted as strategy of turbulence modeling. Results obtained with a hybrid mesh show satisfactory agreement when validated against experimental data and other computational results from the literature. Particular attention is devoted to the effects of the spanwise extension of the computational domain. Results show that the common choice of a spanwise period equal to the chord of the cylinder might not be enough to allow the natural loss of correlation of the pressure fluctuations and the free development of large-scale turbulent structures. The key role played by the amount of numerical dissipation, which is introduced by the second-order central difference scheme used to discretize the inviscid fluxes in the governing equations, is highlighted. The promising results obtained with DES for this benchmark test case suggest that this hybrid method is well suited for complex problems of high-Reynolds number bluff body aerodynamics and fluid-structure coupling.