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

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 ω′yand ω′z. 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, ω′y, and ωz),the inclination of ω′yby ?w/?y, the turn of z by ?v′/?z, and the horizontal shear of z by ?w′/?x are suppressed due to the presence of SWO, leading to attenuation of the turbulent enstrophy.