The user must define at least one segment on the upstream face to determine the upstream openings of hydraulic passage. The segment selected for the openings must be linear. In addition, the user may only consider certain segments in the evaluation of the wet surfaces of the upstream face. Using the Choice of Upstream Face Segments command a dialogue box opens, showing all the available segments, as shown in Figure 56. The same is true for the definition of downstream face segments, which contains the downstream openings and is identical to the definition of upstream segments presented in Figure 56.

Figure 56

In the event of a crest overtopping, CADAM3D must identify the segments defining the crest. Consistent with the definition of upstream face segments, the crest segments are identified using the Crest Segments command. Crest segments cannot be associated with either the upstream or downstream face segments. A segment may also remain unassociated. If the user does not define a crest segment, CADAM3D cannot evaluate the impact of overtopping.