OOF2: The Manual
SegmentSide — The side of an element edge on which output data should be computed.
When evaluating an
Segment separating two
Elements, the result may depend upon whether
the evaluation point is considered to be in one
Element or the other,
Fluxes may be discontinuous at the boundary.
boundaries are directed, having a beginning and an end, so
it's possible to specify which
Element to use for the evaluation by
choosing the one on the left or right side of the boundary.
“Left” means “On the left if you were on the
boundary and facing towards its end.”
If a boundary is external and only has an
Element on one side, that
element will be used regardless of the