二次元画像処理流速計による180°急激曲がり部を有する平滑および90°リブ付き往復流路内乱流の速度場計測

This study experimentally deals with turbulent flow inside smooth and transverse-rib-roughened square two-pass channels in stationary condition. Details of the two-dimensional flow field were quantitatively measured by using a particle image velocimetry which has high spatial- and time-resolution. In the transverse rib case, reattachment and recirculation behind the rib, and small separation bubble in front of the rib were observed. High turbulence intensity in front of the rib as a result of highly fluctuating unsteady fluid motion was clearly captured. Furthermore vortices caused by the sharp turn were observed in the secondary flow.