Abstract

A mathematical model for the evolution of pulsed laser-irradiated, molten metallic films has been developed using the lubrication theory. The heat transfer problem that incorporates the absorbed heat from a single laser beam or the interfering laser beams is solved analytically. Using this temperature field, we derive the 3D long-wave evolution PDE for the film height. To get insights into dynamics of dewetting, we study the 2D version of the evolution equation by means of a linear stability analysis and by numerical simulations. The stabilizing and destabilizing effects of various system parameters, such as the reflectivity, the peak laser beam intensity, the film optical thickness, the Biot and Marangoni numbers, etc. are elucidated. It is observed that the film stability is promoted for such parameters variations that increase the heat production in the film. Moreover, when the heat conduction in the thin substrate is taken into account, the film with non-zero reflectivity is stable with respect to small perturbations in some interval of the optical thickness parameter. In the numerical simulations the impacts of different irradiation modes are investigated. In particular, we obtain that in the interference heating mode the spatially periodic irradiation results in a spatially periodic film rupture with the same, or nearly equal period. Small values of the capillary number result in ring rupture. The 2D model qualitatively reproduces the experimental observations to-date and displays some new effects (Phys. Rev. B 80, 075402 (2009)).

Disciplines

Applied Mechanics | Fluid Dynamics | Materials Science and Engineering | Nanoscience and Nanotechnology | Non-linear Dynamics | Numerical Analysis and Computation | Partial Differential Equations | Transport Phenomena

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