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

Abstract

The Xu & Yan scale-adaptive simulation (XY-SAS) 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 a/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 of λ/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 of λ/Dm. The free shear layer becomes much more stable and rolls up into mature vortex only further downstream when λ/Dm falls in the range of 5–7. The amplitude ratio a/Dm greatly changes the separation line, and subsequently influences the wake structures.