Flow characteristics of drag reducing fluids near the wall surface and turbulent drag reduction mechanism

采用粒子跟踪测速技术结合倏逝波照明技术，对微通道内聚合物稀溶液和蒸馏水在壁面附近的速度分布进行了研究。使用直径为20 nm的荧光颗粒对蒸馏水的速度分布所获得的结果发现，壁表面附近的速度分布的分辨率从常规结果显著提高。另一方面，聚合物稀溶液的速度分布较蒸馏水明显增大，且速度分布的梯度随聚合物分子量的增大而增大。

The velocity profile of dilute polymer solutions and a distilled water near the wall surface in a microchannel was clarified using a particle tracking velocimetry technique combined with evanescent wave illumination. The results obtained for the velocity profile of a distilled water using fluorescent particles with a diameter of 20 nm was found that the resolution of the velocity profile near the wall surface was drastically improved from the conventional result. On the other hand, the velocity profile of dilute polymer solutions increased significantly compared with that of distilled water, and the gradient of the velocity profile increases with the increase of the molecular weight.