ABSTRACT

A simple control algorithm to determine wall deformation with wall variables is investigated based on physical arguments of turbulent coherent structure near the wall. It is found that the spanwise gradient of wall shear stresses are good indicators of strong quasi-streamwise vortex accompanied by the meandering of streak.
The performance of the proposed feedback control with wall variables and using arrayed deformable actuators is examined by using direct numerical simulation of turbulent channel flow. The mean friction drag is found to be reduced by 10%.