Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (5): 1257-1266.doi: 10.3866/PKU.WHXB201603072

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Fluorescence In situ Observation of the Interfacial Dynamics and Adhesion Behaviors of Water and Oil Droplets in a Confined Geometry

Xiang LIU*(),Jin-Tao WANG,Yue ZHANG,Zhan-Hong LI,Chang-Hong XU,Lin TONG   

  • Received:2015-12-31 Published:2016-05-07
  • Contact: Xiang LIU
  • Supported by:
    the National Natural Science Foundation of China(51475440)


As a main source of lubricant contamination, water is one of the most important causes of failure and life reduction of lubricants and mechanical systems. To simulate the interfacial behaviors of real heterogeneous systems, a high-precision point contact experiment apparatus was constructed to study the classical immiscible displacement problem. The interfacial behaviors between water and oil, which are always carried out in the static and parallel space, have been extended to the dynamic point contact wedge in a confined space. The interfacial behaviors of water droplets invading the oil pool around the dynamic point contact region were investigated. Emphasis is placed on the influences of the wettability and the relative separation motion of the solid surfaces on the dynamic behaviors of the droplets. The spreading coefficient has been determined to be the key parameter influencing the coalescing and separating behaviors of the two-phase interface. The influence of the wettability of the solid surface and the relative separation between the ball and the disc on the final coalescing form has been determined. Surface tension and adhesion energy are used to interpret these observations.

Key words: Confined space, Interfacial behaviors of water and oil, Coalescence of immiscible liquid droplet, Wettability of solid surface, Adhesion, Droplet distribution


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