Scale-adaptive simulation of flow past wavy cylinders at a subcritical Reynolds number

摘要

The Xu &Yan scale-adaptive simulation (XYSAS) model is employed to simulate the flows past wavy cylinders at Reynolds number 8 × 103.This approach yields results in good agreement with experimental measurements.The mean flow field and near wake vortex structure are replicated and compared with that of a corresponding circular cylinder.The effects of wavelength ratios λ/Dm from 3 to 7,together with the amplitude ratios α/Dm of 0.091 and 0.25,are fully investigated.Owing to the wavy configuration,a maximum reduction of Strouhal number and root-meansquare (r.m.s) fluctuating lift coefficients are up to 50% and 92%,respectively,which means the vortex induced vibration (VIV) could be effectively alleviated at certain larger values ofλ/Dm and a/Dm.Also,the drag coefficients can be reduced by 30%.It is found that the flow field presents contrary patterns with the increase ofλ/Dm.The free shear layer becomes much more stable and rolls up into mature vortex only further downstream whenλ/Dm falls in the range of 5-7.The amplitude ratio α/Dm greatly changes the separation line,and subsequently influences the wake structures.