Breakup of Thin Liquid Filaments on Partially Wetting Substrates: from Micrometric to Nanometric Scales

J. A. DIEZ; A. G. GONZÁLEZ

BRAZILIAN JOURNAL OF PHYSICS

SOC BRASILEIRA FISICA

Lugar: SAN PABLO; Año: 2015 vol. 46 p. 225 - 237

0103-9733

We present theoretical and experimental resultsregarding the instability of a thin liquid film in the form along filament sitted on a solid substrate. We consider thisproblem in two different scenarios, namely, at submillimet-ric and nanometric scales, and we study their free surfaceinstability. In the first scale, we take into account the effectsdue to surface tension and gravity, while in the smallerscale, we add intermolecular interaction and neglect gravity.The flows are modeled within the long wave approxima-tion, which leads to a nonlinear fourth-order differentialequation for the fluid thickness. This model equation alsoincludes the partial wetting condition between the liquid andthe solid. In the theoretical models, we analyze the linearstability of the equilibrium configurations. The linear sta-bility analyses lead to eigenvalue problems that are solvedusing pseudo spectral methods in the submillimetric case,and finite differences in the nanoscale. Whenever possible,the theoretical results are compared with experiments per-formed on a submillimetric scale (silicon oils on glass), aswell as on nanometric scale (nickel films melted by laserirradiation on SiO2 substrates).