Influence large-scale streamwise vortical EHD flows on wall turbulence

The influence of large-scale electrostatically induced streamwise vortical flows superimposed on turbulent plane channel flow driven by a pressure gradient was analyzed using direct numerical simulation. This study may be relevant for designing a new drag-reduction optimized configuration for electrostatic precipitators. The EHD flows had a spanwise periodicity of 340 wall units. Regardless of intensity, EHD flows induce an initial transient of similar to600 shear-based time units with moderate drag decrease (similar to6-7%), followed by a steady state with slight drag modification. The behavior of shear stress at the wall was examined in connection with the shape of the EHD flows to identify future directions for further drag reduction