Simulation Analysis of the Influence of Operating Parameters on the Pressure Profile in the Coating Bead

In-depth analysis of the pressure profile of coating beads of slot die coating is helpful to better understand the behavior of the flow field in a coating bead and to better obtain a stable coating bead. In this study, ANSYS Fluent 19.2 was used to simulate slot die coating. The simulation results clearly show the influence of various operating parameters on the state of the coating bead and the pressure profile in the coating bead. The results show that the pressure profile can be clearly changed by changing the flow rate, substrate speed, and downstream die lip length. Simultaneously increasing the substrate speed from 0.08 to 0.12 m/s and the average inlet velocity from 0.02672 to 0.04 m/s results in an increase in maximum pressure from 298 to 538 Pa. Increasing only the substrate speed, from 0.12 to 0.16 m/s, causes the maximum pressure to decrease from 538 to 195 Pa. Increasing only the average inlet flow velocity, from 0.027 to 0.04 m/s, leads to an increase in maximum pressure from 167 to 745 Pa. Extending the downstream die lip length from 0.4 mm to 1 mm results in an increase in maximum pressure from 189 to 471 Pa. Reducing the upstream coating gap from 0.3 to 0.1 mm results in significant changes in the pressure profile in the upstream direction. Changing the contact angle can affect the pressure profile in the coating bead, but this is not clear. Changing the coating liquid density at a Reynolds number less than 1.733 has less effect on the pressure profile.