J. Berthier, K. Brakke, Jing Lee, D. Gosselin, F. Navarro, A. Theberge, E. Berthier
Keywords: spontaneous capillary flow, two-phase microflow, plug
Summary:The use of capillarity to move fluids at the microscale has been soaring lately due to new applications in medicine, biology, biotechnology, energy, thermic and space. Especially of interest are open capillary channels. These channels have been designed and fabricated so that a fluid is self-propelled by capillary forces, even in presence of an open boundary with the surrounding air. A universal geometrical criterion for determining the capillary flow onset has recently been derived for closed or open channels. The case of two-phase capillary microflows is naturally the next step of the development of capillary solutions. So far, there is no report in the literature of any result in this domain. In this work, the bases for the understanding of two phase capillary flow are presented. In the presentation, the conditions for single-phase spontaneous capillary flows (SCFs) will be first enounced, for uniform cross section channels and varying cross section channels. Then the case of the capillary flow of a liquid meeting an immiscible plug will be developed. Finally the concept of capillary wagons will be presented.