ABSTRACT
In this chapter, we begin by describing the essence of the famous/infamous ‘moving contact-line problem’, i.e., the problem arising when the process of displacement of one fluid by another immiscible fluid from a solid surface is modeled in the framework of classical fluid mechanics. Then we will review the relevant experiments dealing with various aspects of the liquid-fluid displacement process and analyze the theories proposed in the literature as possible solutions to the problem. The theories will be examined against both the basic criteria to be satisfied by a mathematical theory that we formulated in §2.5.2 and the experimental results. Finally, we will identify the physical mechanism which is at the core of the liquid-fluid displacement phenomenon and discuss its role in other ‘paradoxical flows’ outlined at the end of the previous chapter.
