Abstract

Drag reduction effect by traveling wavy wall deformation control in turbulent pipe flow was experimentally investigated. From the visualization, we confirmed the downstream traveling wave although it was not uniform in the circumferential direction. When the frequency is 110 Hz, the wall deformation amplitude and the wavelength indicated that the effective values for drag reduction. The wavespeed is approximately effective values for drag reduction. As a result, the maximum drag reduction rate of 6.8 % is obtained. The result of a LDV measurement shows that the mean streamwise velocity gradient decreased near the wall by the control, which leads to drag reduction.

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