Control of turbulent channel flow using a plasma-based body force

• The plasma-based body force can substantially suppress wall turbulence.
• Two opposite effects of the body force are indentified to account for skin friction.
• The body force in channel flow can reduce mean skin-friction drag by 13.4%.
• Besides jet-like flow, a new mechanism for suppressing turbulence is proposed.

A steady streamwise co-flow body force originated by plasma actuators was used to control wall turbulence. The effects of such plasma-based body force on channel flow were investigated by direct numerical simulations. We found such body force can suppress turbulence fluctuations. The underlying mechanism was proposed in the discussion of Reynolds-stress budget and turbulent structures. To explore the possibility of drag reduction, we examined the skin-friction coefficient Cf in the controlled flow. Two opposite effects were identified to account for the behavior of Cf. The first is large streamwise velocity gradient in the normal direction at wall induced by the body force, thus large increase in Cf occurs over the forcing region. The second is reduction in the Reynolds stresses, which will contributes to the decrease in Cf. Away from the forcing region, the skin-friction coefficient rapidly decreases, even less than that of the baseline. Furthermore, force strength and spacing were considered in the parametric study. The results showed that the plasma-based body force can reduce mean skin-friction drag by 13.4%.