Numerical analysis of pulsatile flows in a slot-die manifold

We analyze the effects of inlet periodic pulsatile flows on the flow inside a slot-die manifold for different locations of the inlet feed port. This type of flow rate disturbance can be caused by a coating liquid pumping mechanism that may lead to coating thickness nonuniformity. In this study, we analyze the transient behavior of the three-dimensional flows inside the slot-die manifold using parallel finite element computations. For a small magnitude of inlet flow rate disturbance with a given frequency, the local flow rate per unit width and the velocity profile at the feed slot exit become periodic. Therefore, the amplification factor can be used to quantify the effect of the inlet pulsatile flows. We found that the flow inside the feed slot, which is the confined channel with a high aspect ratio, dominates the dynamics of the outlet flow. However, the overall trend of the amplification factor along the cross-web direction resembles the steady-state pressure profile inside the cavity, and hence the steady-state profile of the outlet flow rate per unit width, which is strongly affected by the choice of the inlet port location.