マイクロファイバ壁面による抵抗低減流れのPIV計測(流れの制御(1),一般講演) PIV Measurement of Drag Reducing Turbulent Flow on Implanted-Microfiber Wall

Implanted-microfiber wall has been investigated as a passive control for turbulent drag reduction. A maximum drag reduction of 50% has been reported in (1). However, the mechanism of the turbulent drag reduction has not been examined. The purpose of this study is experimental investigation of the mechanism of turbulent drag reduction in a turbulent channel flow on a microfiber wall with PIV measurement. A maximum drag reduction of about 11% has been obtained, and drag-reduction phenomenon has been confirmed in the wide range of the Reynolds number (Re_b≈7000～15000). It is observed through PIV measurement that instantaneous spanwise streak spacing is increased compared with that for the flat-surface case.