微尺度流动界面现象及其流动边界条件分析

Interfacial phenomena in micro-scale flowing and its flowing boundary condition

水平微尺度毛管中低Reynolds数流体流动出现许多另人费解的现象,如流动前缘并未出现Poiseu ille速度剖面,而似一种“段塞式”流动,固/液界面看似不符合无滑移边界条件。该文针对这些易引起困惑的问题,利用可视化微管流动实验及岩石孔隙仿真光刻模型流动实验,考察了润湿性对微尺度毛管中流体流动的影响,探讨了微尺度毛管中表面流动现象产生的实质。结果表明,在微尺度流动中观察到的小分子液体“段塞流动现象”,以及看似壁面滑移流动等现象,其实质是液/固壁面仍为无滑移边界,三相接触点以尤如运动的“坦克的链轨”发展方式,沿壁面发展,从而产生“段塞式”流动。虽然仍在低速层流的条件下,但由于界面张力的作用,接近动界面处流动质点的运动已不再保持一维直线运动。

In horizontal micro-scale capillaries, micro molecule liquid flows at low Reynolds number appear many phenomena which are difficult to understand, such as the flowing front of being like a slug flow does not have Poiseuille velocity profile, and the solid-liquld interface does not look like to follow no slip boundary condition. As to these problems, visual flowing experiments in micro-scale capillaries and rock simulation models have been implemented, and the effect of wettability on the flow in micro scale capillaries have been studied. The results show the inbeing of the slug flow and apparent wall sliping phenomenon is the solid liquid interface, which is still in accord with no slip boundary condition, and the movement of three-phase junction likes a tank runing gear to flow on the wall of capillary due to wall wettability. Thought the flow is at low Reynold number, the flowing particles near the front interface do not move along a straight line due to interfacial intension.