Flow Simulations of Dynamic Wetting Line at a Reverse-roll Coater Using the VOF Method

Flow simulations at reverse-roll coater using the VOF method were performed. In these simulations velocity fields and pressure fields were calculated in the gas phase and the liquid phase simultaneously. Concerning stream lines of the liquid phase, a large vortex and a small vortex are observed. Stream lines with various speed of the metering roll were simulated. Dynamic wetting line approaches to the center line of the nip with increasing the speed of the metering roll. Pressure distribution between the two rolls has two peaks which are a positive and a negative. Negative peak of pressure increases with the speed ratio S increases. Dynamic contact angle θD and dynamic wetting line position XD were calculated and compared with experimental data. The calculated value of θD and XD were in good agreement with the experimental value.