Experimental Study on Drag Reduction Effect With Traveling Wave Control Using PIV Measurement

The influence of the traveling wave control on flow fields is evaluated by experiments using a traveling wavy wall in a fully developed turbulent dual channel flow. We develop a traveling wave generator using a rubber sheet and piezoelectric actuator as a vibration source. A single piezoelectric actuator is installed in the upstream position of the channel. Experiments are performed using traveling waves attenuating in the downstream direction. With traveling wave control, effective drag reduction is confirmed when bulk Reynolds number is within the range of 2000 < Reb < 6000. For Reb = 3000, the maximum drag reduction rate of 10% is obtained. In order to evaluate a relationship between the amplitude attenuation of traveling wave and drag reduction effect, particle image velocimetry (PIV) at multiple positions is performed. Increase of drag is observed near the vibration source whereas drag decreased at other positions. Reduction of random component of Reynolds shear stress can be ascribed to the drag reduction.