DISCUSSION
The creeping flow model is singular and therefore unrealistic in the corner of each of the two fluid phases at a moving line of contact. Shear stresses, pressure, and viscous dissipation rate increase without bound as the contact line is approached. Neither the shape of the solid surface nor the nature of the bulk fluids is primarily responsible. From a mathematical viewpoint these deficiencies of the model stem from the velocity discontinuity on the boundary: the adherence condition is imposed (Eqs. [8] and [9]) at the solid where r > 0 but at r = 0 perfect slip of the contact line itself is demanded.
Now singularities in mathematical physics usually signal failure of one or more hypotheses underlying the model, for nature abhors local infinities. The most obvious culprit here is the adherence, or "no-slip," condition but there are other suspects: where pressure in the liquid plunges and viscous dissipation mounts there may be ; short of that there may be steep gradients of viscosity and density and appreciable compressibility effects; just as ordinary fluid no longer follows bulk equations of state when it is in interfacial transition zones, so also may it behave still differently when it is in contact-line zones the Newtonian constitutive relation may very well fail as the contact line is approached in either fluid phase; accumulation or depletion of surfactant or heat in the interface might cause an interfacial tension gradient in the interface near the contact line. The presence of the corners of fluid insures that there is a neighborhood of the contact line in which long-range inter- molecular forces (electrostatic and dispersion forces) take on special importance, and a still smaller neighborhood the linear dimensions of which approach molecular dimensions and in which the conventional continuum approach either fails or must be drastically reinterpreted. On this scale the contact line is seen as a zone and it is not at all clear how it might grade into the three zones that merge into it (44).
这里的翻译好像根本就没有结束,大部分都没有翻译呀,可否在帮忙一下呢?