Contact line static

Sillinian, W. J. and Scriven, L. E., 1980. Separating flow near a static contact line slip at a wall and shape of a free surface.. /. Comput. Phys. 34, 287-313. 

Dussan EBV (1979) On the spreading of liquids on solid surfaces static and dynamic contact lines. Ann Rev Fluid Mech 11 371 00... 

While the above refers mainly to the static limit, new effects come into play when a moving contact line, i.e. spreading, is considered. It has been observed experimentally that the contact angle of a moving contact line 0, the dynamic contact angle, deviates from the corresponding static value 0. As an example, for a completely wettable surface (i.e. 6(, = 0), a relationship of the form... 

However, not only the contact lines themselves are beneath all the points but their slope is also too small to explain the true concentration dependence. Perhaps these difficulties stimulated Stevens to propose the original finite-sink approximation instead of the existing theory [103,250]. The inconsistency of this model is seen from the very fact that it does not discriminate between the Stem-Volmer and the steady-state constants, k and k = lim, >rXj k(t), and ascribes to the latter the concentration dependence, which is not inherent to k in principle. At the same time the model predicts the linear dependence of the results in coordinates 1/k versus c1/3, and this linearity was confirmed experimentally a number of times [6,248,250,251], According to their finite-sink model [248], the straight lines representing this dependence for different temperatures should intersect at a common point where the static quenching limit is unambiguously located. ... 

Davis SH. (1980) Moving contact lines and rivulet instabilities. Part 1. The static rivulet. J Fluid Mech 98 225-242. 

ADSA-P has been employed in various surface tension and contact angle studies, including static (advancing) contact angles [69.70], dynamic (advancing) contact angles at slow motion of the three-phase contact line [4, 71—74], and contact angle kinetics of surfactant solutions [75]. A schematic of the experimental setup for ADSA-P sessile drops is shown in Fig. 6. More details are available elsewhere [66[. 

Hysteresis is a static phenomenon, but its measurement requires displacement of the contact line (fig, 5.4). Immediately the question is raised as to what are the... 

After the static test mentioned above, the method is now tested for the impact and spreading of a glycerin droplet on a wax substrate and the computational results are compared with the experimental data of Sikalo et al. [32], The details of the experimental setup, material properties and computational model can be found in Refs. [33, 51]. The computed and experimental spread factor and contact line are plotted in Figs. 19a and b, respectively. These figures show that the present front-tracking method is a viable tool for simulation of interfacial flows involving moving contact lines. 

Fig. 10.1.4. The liquid may spread freely over the surface, or it may remain as a drop with a specific angle of contact with the solid surface. Denote this static contact angle by 6. There must be a force component associated with the liquid-gas surface tension (t that acts parallel to the surface and whose magnitude is a cos 0. If the drop is to remain in static equilibrium without moving along the surface, it has to be balanced by other forces that act at the contact line, which is the line delimiting the portion of the surface wetted by the liquid, for example, a circle. It is assumed that the surface forces can be represented by surface tensions associated with the solid-gas and solid-liquid interfaces that act along the surface, and tr i, respectively. Setting the sum of the forces in the plane of the surface equal to zero, we have...

At the edges of the coated layer its free surface ends in ordinary static contact lines. These lateral contact lines necessarily bend round upstream and connect with the wetting line. Thus at each edge of the layer where it is being delivered to the substrate there must be a curved segment of dynamic contact line, and the apparent slip of the liquid... 

Within a feasibility window lie coating quality windows defined by features and sensitivities of the flow states. Similar augmented continuation schemes make it possible to track through parameter space the limiting states at which a microvortex appears or disappears, a static contact line pins to an edge or moves free, a machining flaw creates an unacceptably thick streak, and so forth - and in addition to see how the feasibility and quality windows depend on shape and dimensions of the coating applicator. 

For completeness, it should be mentioned that flywheels or static converters (for example, generating a local network from the railways contact line) are used in niches. 

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