Inlets which overlap the computation grid for 2D calculations are handled differently from inlets outside of the grid. Equivalent inlet capture curves are generated for SWMM based on the inlet type (HEC-22, Maximum Capture, etc…) and its physical dimensions. The 2D engine utilizes these capture curves along with the grid surface flow and depth at the concurrent cell to compute flow into the subsurface system.

If the inlet on the grid is the outflow element for a catchment, this flow is injected directly into the system, so flow is not lost. Any flow via a gutter link, that begins outside the grid, into a coupled inlet is injected directly into the piped system as well.

All inlets outside of the computation grid, will computed in the same fashion if you computed them using the SWMM engine alone.