MMN, UMR CNRS Gulliver 7083, PSL research University, ESPCI ParisTech, 10 rue Vauquelin, F-75005 Paris, France.
LOF, unité mixte Solvay-CNRS-Bordeaux 1, 178 avenue du Docteur Schweitzer, F-33608 Pessac cedex, France.
Phys Rev Lett. 2014 Jun 13;112(23):238302. doi: 10.1103/PhysRevLett.112.238302. Epub 2014 Jun 10.
We investigate the drainage of a 2D microfoam in a vertical Hele-Shaw cell, and show that the Marangoni stress at the air-water interface generated by a constant temperature gradient applied in situ can be tuned to control the drainage. The temperature gradient is applied in such a way that thermocapillarity and gravity have an antagonistic effect. We characterize the drainage over time by measuring the liquid volume fraction in the cell and find that thermocapillarity can overcome the effect of gravity, effectively draining the foam towards the top of the cell, or exactly compensate it, maintaining the liquid fraction at its initial value over at least 60 s. We quantify these results by solving the mass balance in the cell, and provide insight into the interplay between gravity, thermocapillarity, and capillary pressure governing the drainage dynamics.
我们研究了在垂直亥姆霍兹微流控通道中二维微泡沫的排出，结果表明，通过施加恒定温度梯度原位产生的气-液界面马兰戈尼应力可以被调节来控制排出。采用这样的方式施加温度梯度，以使热毛细流和重力产生拮抗作用。我们通过测量通道内的液体体积分数来描述随时间的排出过程，并发现热毛细流可以克服重力的影响，有效地将泡沫向上排出通道，或者完全补偿其影响，使液体分数在至少 60 秒内保持初始值。我们通过求解通道内的质量平衡来定量这些结果，并深入了解控制排出动力学的重力、热毛细流和毛细压力之间的相互作用。
