Dynamics of Spreading

Baker observed mobilization of small particles of several metals and metal oxides on graidiite at a temperature (so-called mobility temperature ) that was identical with the Tammann temperature. Ilius, in systems exhibiting relatively weak interactions with the support surface, particle mobility may be induced at this temperature which might ultimately lead to agglomeration rather than spreading. 

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M. Voue, M. P, Valignat, G. Oshanin, A. M. Cazabat, and J. De. Coninck, Dynamics of spreading of liquid microdroplets on substrates of increasing surface energies, Langmuir 14, 5951-5958 (1998). 

De Gennes (1985) analysed the static and dynamic problems of different wetting phenomena. In this book only the dynamics of spreading and the wetting transition are of interest. Wetting transition takes place at a characteristic temperature where the contact angle diminishes and a wetting film is formed. 

For a given liquid, the dynamics of spreading is found to be independent of the solid, as soon as complete wetting is achieved (S > 0). This is very surprising as the (horizontal) unbalanced capillary force for spreading is now... 

The observed power laws can be found theoretically by hydrodynamical calculations in the S = 0 case. For strictly positive values of S and volatile liquids, one might argue that the drop spreads on a preexisting liquid film and that the true value of S is zero. But the paradox remains in the case of nonvolatile liquids. Why is the dynamics of spreading independent of S ... 

As a general summary, the dynamics of spreading and dewetting is controlled by the balance of driving forces (e.g., capillary forces, gravity, or electric forces) and resistance due to dissipative processes that maybe increasingly more complicated when complex fluids rather... 

Similar calculations can be carried out for the dynamics of spreading of a one-dimensional droplet (cylinder), which results in... 

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