Minimum film thickness of slot coating with a volume of fluid technique

Abstract

Oil is the base of modern industrial economies, but the capacity to maintain the world oil production is becoming difficult. Also, recent studies show that the oil production will attain a peak in the next years. In this scenario, alternative sources of energies are important to help in the inevitable transition to low carbon sources. Photovoltaic solar energy is an att ractive option, but it is still expensive if compared to traditional sources, although this cost difference is becoming lower in the last decades, it is still not enough. One way to reduce the cost of solar cells is to use a thinner coating thickness. This work presents the numerical simulation of the slot coating process of Newtonian fluids, with the volume of fluid technique in order to determine the low-flow limit. The obtained numerical results compares very well with the viscocapillary model’s results. It is verified that the minimal wet coating thickness, before the defect, increases with the capillary number, which means that thinner films will be obtained if the velocity of the process is low.

Keywords: VOF, two-phase flow, low-flow limit,slot coating.