Keita Emmanuel, Koehler Stephan A, Faure Paméla, Weitz David A, Coussot Philippe
Laboratoire Navier, Université Paris-Est, Paris, France.
School of Engineering and Applied Sciences and Physics Department, Harvard University, Boston, USA.
Eur Phys J E Soft Matter. 2016 Feb;39(2):23. doi: 10.1140/epje/i2016-16023-8. Epub 2016 Feb 26.
We look at the drying process in a simple glass channel with dominant capillary effects as is the case in microfluidics. We find drying kinetics commonly observed for confined geometry, namely a constant period followed by a falling rate period. From visualization of the air/water interface with high resolution, we observe that the drying rate decreases without a drying front progression although this is the usually accepted mechanism for confined geometries. We show with FEM that in our specific geometry the falling rate period is due to changes in the shape of the air-water interface at the free surface where most evaporation occurs. Our simulations show that the sensitivity of the drying rate to the shape of the first air-water interface from the sample free surface implies that slight changes of the wetting or pinning conditions can significantly modify the drying rate.
我们研究了在具有主导毛细作用的简单玻璃通道中的干燥过程，这在微流体中是常见的情况。我们发现了在受限几何形状中通常观察到的干燥动力学，即先是一个恒定阶段，随后是一个降速阶段。通过高分辨率可视化空气/水界面，我们观察到干燥速率下降，而没有干燥前沿的推进，尽管这是通常认为的受限几何形状的机制。我们用有限元法表明，在我们特定的几何形状中，降速阶段是由于在发生大部分蒸发的自由表面处空气-水界面形状的变化。我们的模拟表明，干燥速率对样品自由表面处第一个空气-水界面形状的敏感性意味着润湿性或钉扎条件的微小变化会显著改变干燥速率。
