Response of turbulent enstrophy to sudden implementation of spanwise wall oscillation in channel flow

Abstract

The response of turbulent enstrophy to a sudden implementation of spanwise wall oscillation (SWO) is studied in a turbulent channel flow via direct numerical simulation. In the beginning of the application of SWO, a significant correlation is formed between ωy′ and ωz′. A transient growth of turbulent enstrophy occurs, which directly enhances turbulent dissipation and drifts the turbulent flow towards a new lower-drag condition. Afterwards, the terms related to the stretching of vorticity (ωx, ωy′, and ωz), the inclination of ωy′ by \(\frac{\partial w}{\partial y}\), the turn of ωz by \(\frac{\partial v\prime}{\partial z}\), and the horizontal shear of ωz by \(\frac{\partial w\prime}{\partial x}\) are suppressed due to the presence of SWO, leading to attenuation of the turbulent enstrophy.