Stability of vertical films of molten glass due to evaporation

First, we report observations achieved on a gravitationally driven film drainage with molten glass pointing out a stabilizing effect when temperature is larger than 1250 °C. A model to describe the change of surface tension with the film thickness due to the evaporation of oxide species is proposed. A lubrication model is derived taking into account the gradient of surface tension. The final system of equations describing the mass and the momentum conservations is numerically solved by an implicit time solver using a finite difference method at a second order scheme in time and space. merical procedure is applied to study a film drainage of molten soda–lime–silica glass. The effect of the surface tension gradient is investigated pointing out that with an increase of 0.5% of the surface tension over the spread of the film which is order of few centimeters, the liquid film reaches an equilibrium thickness in agreement with previous experimental work.