Unsteady flow past a 5:1 rectangular cylinder: computational investigation on three-dimensional spanwise effects

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 and high Reynolds number. Detached-Eddy Simulation has been adopted as strategy of turbulence modeling. Results obtained with a hybrid mesh are validated against experimental data and other computational results showing good agreement. Particular attention is devoted to the effects of the spanwise extension of the computational domain. Results show that the common choice of a distance between the periodic boundary planes equal to the width of the cylinder is not enough to allow the natural loss of correlation of pressures and the free development of large-scale turbulent structures. Finally the key role played by the numerical dissipation, which is introduced by the scheme used to discretize the convective term in the governing equations, is highlighted.