Dynamics of liquid nanofilms

Henri Gouin (1) , Sergey L. Gavrilyuk (1)

1 IUSTI - Institut universitaire des systèmes thermiques industriels

The van der Waals forces across a very thin liquid layer (nanofilm) in contact with a plane solid wall make the liquid nonhomogeneous. The dynamics of such flat liquid nanofilms is studied in isothermal case. The Navier-Stokes equations are unable to describe fluid motions in very thin films. The notion of surface free energy of a sharp interface separating gas and liquid layer is disqualified. The concept of disjoining pressure replaces the model of surface energy. In the nanofilm a supplementary free energy must be considered as a functional of the density. The equation of fluid motions along the nanofilm is obtained through the Hamilton variational principle by adding, to the conservative forces, the forces of viscosity in lubrication approximation. The evolution equation of the film thickness is deduced and takes into account the variation of the disjoining pressure along the layer.

Mots clés: lubrication approximation; Very thin films; interface motions; lubrication approximation.

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]; Matière Molle [cond-mat.soft]; Chimie-Physique [physics.chem-ph]

Henri Gouin, Sergey L. Gavrilyuk. Dynamics of liquid nanofilms. International Journal of Engineering Science, 2008, 46, pp.1195-1202. ⟨10.1016/j.ijengsci.2008.05.002⟩. ⟨hal-00323322⟩