利用显微粒子成像测速（Micro-PIV）技术测量矩形微通道中

Microscopic particle image velocimetry (microPIV) experiments were performed on a polydimethylsiloxane (PDMS) microchannel
with a cross-section measuring 320 lm · 330 lm for Reynolds numbers between 272 and 2853. Care was taken to ensure that the
seed particle density was great enough that accurate instantaneous velocity vector fields could be obtained for all the Reynolds numbers
investigated. Velocity fluctuations were calculated from ensembles of microPIV velocity fields. The hu0i/umax fluctuation showed
an increase at Re = 1535 and a further increase as Reynolds numbers were increased, suggesting that transition to turbulence began
near Re = 1535, a Reynolds number lower than predicted by classical theory. The hu0i/umax data also suggest the flow was fullydeveloped
at a Reynolds number between 2630 and 2853, also lower than classical results. This finding was confirmed in plots of
the mean velocity profile. For the fully developed flow, the measured hu0 i/umax fluctuation agreed well with classical results for turbulent
duct flow, but the hv0 i/umax fluctuation was 2540% lower than turbulent duct flow results. Finally, spatial correlations of
velocity fluctuations were calculated to lend some insights into the characteristics of the large-scale turbulent structures observed
in the turbulent microchannel flow. 显微粒子成像测速系统(Micro PIV) Imager sCMOS PIV相机