Evolución de filamentos líquidos sobre substratos sólidos

A. G. GONZÁLEZ; J. A. DIEZ

Anales de la Academia Nacional de Ciencias de Buenos Aires

Academia Nacional de Ciencias de Buenos Aires

Lugar: Buenos Aires; Año: 2010; p. 623 - 655

The formation of controlled patterns of drops on solid substrates isrelevant in several technological problems. A possible mechanism togenerate these patterns consists in melting straight or curved nanometricmetal filaments using lasers. The contact line instabilities break up theresulting liquid rivulets leading to the subsequent formation of drops. Similar phenomena have been observed in macroscopic (submillimetric) scales for oil rivulets placed on partially wetted surfaces. Several experiments are analyzed that show aspects not completely understood in these problems. We use optical diagnostics based on laser refraction to characterize the structure of the resulting drops in the macroscopic experiments and evidence the existence of hysteretic behavior. Models that avoid the moving contact line paradox are required to study these experiments. Two alternatives are presented: one based on the van der Waals forces and the other one using a slipping condition. Analytical results and numerical simulations are compared with experimental data in both scales. It is shown that the treatment based in the slipping condition allows solving complex problems like those of rings, which had no satisfactory previous theory.