@Article{CiCP-17-5, author = {}, title = {The Rupture of Thin Liquid Films Placed on Solid and Liquid Substrates in Gravity Body Forces}, journal = {Communications in Computational Physics}, year = {2015}, volume = {17}, number = {5}, pages = {1301--1319}, abstract = {
This paper presents a numerical and experimental study on hydrodynamic
behavior of thin liquid films in rectangular domains. Three-dimensional computer
simulations were performed using the lattice Boltzmann equation method (LBM). The
liquid films laying on solid and liquid substrates are considered. The rupture of liquid
films in computations is initiated via the thermocapillary (Marangoni) effect by
applying an initial spatially localized temperature perturbation. The rupture scenario
is found to depend on the shape of the temperature distribution and on the wettability
of the solid substrate. For a wettable solid substrate, complete rupture does not occur:
a residual thin liquid film remains at the substrate in the region of pseudo-rupture. For
a non-wettable solid substrate, a sharp-peaked axisymmetric temperature distribution
induces the rupture at the center of symmetry where the temperature is maximal. Axisymmetric
temperature distribution with a flat-peaked temperature profile initiates
rupture of the liquid film along a circle at some distance from the center of symmetry.
The outer boundary of the rupture expands, while the inner liquid disk transforms
into a toroidal figure and ultimately into an oscillating droplet.
We also apply the LBM to simulations of an evolution of one or two holes in liquid
films for two-layer systems of immiscible fluids in a rectangular cell. The computed
patterns are successfully compared against the results of experimental visualizations.
Both the experiments and the simulations demonstrate that the initially circular holes
evolved in the rectangular cell undergoing drastic changes of their shape under the
effects of the surface tension and gravity. In the case of two interacting holes, the
disruption of the liquid bridge separating two holes is experimentally observed and
numerically simulated.