  We consider films and filaments of nanoscale thickness on thermally
conductive substrates exposed to external heating. Particular focus is on metal
films exposed to laser irradiation. Due to short length scales involved, the
absorption of heat in the metal is directly coupled to the film evolution,
since the absorption length and the film thickness are comparable. Such a setup
requires self-consistent consideration of fluid mechanical and thermal effects.
We approach the problem via Volume-of-Fluid based simulations that include
destabilizing liquid metal-solid substrate interaction potentials. These
simulations couple fluid dynamics directly with the spatio-temporal evolution
of the temperature field both in the fluid and in the substrate. We focus on
the influence of the temperature variation of material parameters, in
particular of surface tension and viscosity. Regarding variation of surface
tension with temperature, the main finding is that while Marangoni effect may
not play a significant role in the considered setting, the temporal variation
of surface tension (modifying normal stress balance) is significant and could
lead to complex evolution including oscillatory evolution of the liquid
metal-air interface. Temperature variation of film viscosity is also found to
be relevant. Therefore, the variations of surface tensions and viscosity could
both influence the emerging wavelengths in experiments. In contrast, the
filament geometry is found to be much less sensitive to a variation of material
parameters with temperature.
