Effect of LEBU on the wall shear stress in a two-dimensional turbulent channel flow

Abstract

Large Eddy Break Up (LEBU) device has been tested experimentally for the wall shear stress manipulation in a fully developed two-dimensional turbulent channel flow. Measurement of the skin friction coefficient states that LEBU reduces the local wall shear stress. With the wall shear stress reduction, mean velocity gradient and Reynolds shear stress are reduced near the wall. From the wall static pressure drop, no net drag reduction occurs in the channel flow with LEBU manipulation. Influence of LEBU device on the streamwise pressure gradient near the wall is suggested as one of the reasons why velocity gradient and Reynolds shear stress near the wall are reduced in the manipulated flow with LEBU.

Keywords

• turbulence
• channel flow
• flow control
• wall shear stress reduction
• reynolds shear stress