The blockage of flow out of a cavity due to an obstruction caused by contacting surfaces:
can be defined selectively for particular surfaces that may fully or partially cause the blockage; and
can be accounted for only when the surfaces are used with the general contact algorithm.
To consider an obstruction by contacting surfaces as discussed in Accounting for blockage due to contacting boundary surfaces” in “Defining fluid exchange, Section 11.6.3, you must define a surface to represent the leakage area on the boundary of the fluid cavity. In addition, you must specify that the contacting surfaces can potentially cause blockage. All the surfaces (the surface on the boundary of the fluid cavity and the contacting surfaces) must be included in a general contact domain. To account for contact blockage, the nodes on the surfaces must be in node-to-face contact. When the nodes on the surface on the boundary of the fluid cavity come into contact with the contacting surfaces, the slave nodes are marked as active nodes for contact blockage. The contact blockage is also considered in the edge-to-edge contact (see Contact formulation for general contact, Section 29.3.4).
ABAQUS/Explicit determines the obstruction area by calculating the area fraction of the surface on the boundary of the fluid cavity that is not blocked by contacting surfaces. For each element face of this surface representing the leakage area, the blocked area is calculated based on the active nodes for contact blockage. The element blocked area is determined by