Dissipation in dynamics of a moving contact line - art. no. 031601

The dynamics of the deformations of a moving contact line is studied assumi ng two different dissipation mechanisms. It is shown that the characteristi c relaxation time for a deformation of wavelength 2 pi/\k\ of a contact lin e moving with velocity nu is given as tau (-1)(k) = c(nu)\k\. The velocity dependence of c(nu) is shown to depend drastically on the dissipation mecha nism: we find c(nu)=c(nu =0)-2 nu for the case in which the dynamics is gov erned by microscopic jumps of single molecules at the tip (Blake mechanism) , and c(nu) similar or equal toc(nu =0)-4 nu when viscous hydrodynamic loss es inside the moving liquid wedge dominate (de Gennes mechanism). We thus s uggest that the debated dominant dissipation mechanism can be experimentall y determined using relaxation measurements similar to the Ondarcuhu-Veyssie experiment [T Ondarcuhu and M. Veyssie, Nature 352, 418 (1991)].