要約

We analyzed the influence of large-scale ElectroHydroDynamic streamwise vortical flows superim-posed to a plane Poiseuille flow. The vortical flows had a spanwise periodicity of 340 wall units, in order to encompass three low-speed streaky structures. Results indicate that, after the actuation of control flows, the flow field undergoes an initial steep transient of about 600 shear-based time units with a moderate drag decrease (about 6 − 7%), followed by a steady-state in which the overall drag was only slightly affected by the EHD flows. Higher intensity cases led to drag reduction. The long-term effect of flow control is small, being at most about 4 − 5%. Corresponding to such small modification of the overall drag there is no significant change in the structure of turbulence at the wall.