Wetting in pressure driven slot flow

To test wetting models for predicting a range of wetting behaviours in slot flow, we utilize two finite-element techniques to model a fluid displacing air as it flows between parallel plates where the upper plate has a notch perpendicular to the flow direction. The notched portion of the upper plate is representative of a mold joint, a feature in the part to be potted, or even a long scratch in the plate surface. The goal is to study the wetting conditions that can minimize air entrapment in the notch. The numerical tool, developed at Sandia National Laboratories, is used to predict the front movement through the slot. Both a level-set formulation and an ALE formulation are used to track the front with two types of wetting models. A linear relationship between the wetting line velocity and the deviation between the dynamic and static contact angles is used when using the level-set algorithm, while a nonlinear wetting model originated by Blake is used for the ALE calculations. Preliminary results show that the capillary number, or the ratio of viscous forces to surface tension forces, is the dominant parameter. Nevertheless, whether or not the notch fills with liquid is also dependent on the velocity conditions imposed at the triple point.