New insight on large-eddy simulation of flow past a circular cylinder at subcritical Reynolds number 3900

摘要

Flow past a circular cylinder at the subcritical Reynolds number of 3900 is numerically investigated based on large-eddy simulations (LESs) via the open-source toolbox OpenFOAM. Good grid convergence property is achieved for the present LESs with different subgrid-scale models as far as the near-wake statistics are concerned. On the intermediate-resolution grid, current LES data in terms of mean flow and turbulence quantities are in good agreement with the benchmark experimental results. A comparison study on the Smagorinsky model manifests that increasing the model coefficient results in a longer recirculation length and smaller drag and lift coefficients. The budget analysis of the turbulent kinetic energy (TKE) equation suggests that the main source in the wake area is the TKE production, which is transported downstream mainly through the advection by mean flow and further moved upward and downward through the transport terms. The flow patterns indicate that the weak production rates induced by the shear layers delay the downward movement of the mean flow, resulting in a longer recirculation region. This dynamic picture provides a reliable explanation for the differences in the recirculation length and mean flow profiles observed in the near-wake area from different experimental and numerical studies.