Large-eddy simulation of flow past a circular cylinder for Reynolds numbers 400 to 3900

Abstract

The benchmarking case of flow past a circular cylinder at the Reynolds number (Re) of 3900 is computed with two open-source codes, OpenFOAM and Nektar++, which are based on the conventional finite volume method (FVM) and the high-order spectral/hp element method, respectively. By using the Nektar++ model, mesh convergence for the case Re = 3900 is demonstrated (perhaps for the first time) through a systematic mesh dependence study, which includes separate examinations of the spanwise domain length (Lz/D), spanwise resolution, and the resolution in the plane perpendicular to the spanwise direction. The computational efficiencies for the Nektar++ and OpenFOAM approaches are then compared. This benchmarking study adds value to the broad Nektar++ and OpenFOAM communities and to the numerical modeling of bluff-body flows in general. Based on the Nektar++ approach, the computations are then generalized to a range of Re = 400-3900. It is found that Lz/D = 3 is adequate for Re = 2500-3900, while an increased Lz/D = 6 is recommended for Re = 400-2000. Based on the present high-fidelity numerical data, the physical mechanisms for the variations in the wake recirculation length and the hydrodynamic forces and pressure on the cylinder with Re are explored. In particular, the physics behind the inverse correlation between the root mean square lift coefficient (CL′) and the wake recirculation length, which includes a significant decrease in CL′ over Re = 270-1500, is highlighted.