Abstract:At a classical sub critical Reynolds number (Re=3 900), a numerical simulation was performed for the flow over a circular cylinder by large eddy simulation (LES) method with Smagorinsky sub grid model. The mean integral quantities were compared with the existing results to confirm the numerical results. The mean flow and turbulence characteristics were analyzed and the wake structures were performed. In addition, the differences between numerical results and early experimental results were explained and the index effect of the recirculation length was found.