Nonlinear dynamics of three-dimensional long-wave Marangoni instability in thin liquid films

The three-dimensional evolution of the long-wave Marangoni instability of thin liquid films is studied. According to earlier theoretical predictions no continuous steady states exist and the film ruptures. As in two dimensions, the mechanism of fingering is found to be a main route to rupture. A four-fold rotational symmetry of the film interface is retained, when a square periodic domain and the harmonic initial disturbance are used. A use of initial random disturbances in general eliminates the square symmetry of the solution. An increase of the domain size results in a growing complexity of the emerging patterns. In contrast with the dynamics in two dimensions the evolution of the interface in three dimensions and in particular the pattern emerging at rupture may strongly depend on the choice of the initial condition. The two-dimensional evolution of the film is found to be unstable to small three-dimensional random disturbances. (C) 2000 American Institute of Physics. [S1070-6631(00)00707-8].