Bulk fluid, rupture

With the more conductive liquids, the ion concentration becomes so great that ion concentration fluctuations on a statistical basis are likely to be small. However, charging can take place by three other mechanisms (1) mechanical disruption of any double layer of ions that may exist at the surface in times that are short compared with the relaxation time, with a predominance of the surface ions going to the portion of fluid coming from the surface (2) unequal ion mobility with the larger ions unable to return to the bulk of liquid as readily as the smaller and more mobile ones and (3) contaminating materials, such as dust or surfactants at the interfaces serving as ion carriers into one portion or the other of the ruptured liquid. 

In this method a large bulk of one of the fluids is broken into smaller particles inside a continuous phase of the other fluid. This can be caused either by an artificial stirring action or by the instability of the big globule itself. A typical example of this method is the rupture of bubbles during their ascent in a stirred-tank reactor. 

If the idealized concept of fluid film failure proposed above is to have any significance in the world of experimental mechanics and engineering, we must find a basis for its validity and utility. The study of fluid film failure in a practical sense then becomes the study of the behavior of the boundary surfaces of the solids and of the intervening fluid lubricant as the thickness of the lubricant film approaches zero. An important aspect is the reliability of the measurement technique for very thin films. We must be careful not to think of fluid film failure as rupture or breakdown by exceeding the intrinsic strength of the lubricant material. Bulk liquid films do not behave in that way. We know by hydrodynamic theory that the pressure a film of fluid is able to... 

To induce coalescence the apparatus was inclined, moving the free drop back towards the stationary one. Since the two drops were far apart initially, by the time the free drop neared the stationary one the stationary drop had already reached its new equilibrium shape. The droplets appeared to contact each other (see Figure 5) at which time an extremely thin film of bulk phase fluid separated the droplets. The time interval between apparent contact and film rupture was taken as the coalescence time. 

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