[ldetwiler]

Jennifer, thank you for setting up this thread. I hope your wormhole woes are long gone. Maybe one of you all has the wisdom I need:

I’m running a simple wormhole culvert in order to maintain a single 2D mesh while managing to convey flow under a canal within that 2D area. I’m practically certain that I’ve drawn the wormhole in a way that respects the procedure outlined in Con Katsoulas’ explanation, and I am succeeding in producing flows through the culvert, but the culvert hydrograph makes me suspect issues:

In, you’ll note an US invert of 652.5 ft and DS of 648.54 ft for the 170 foot CMP culvert, and you can see that both the inlet and outlet are above the terrain surface. Though, the following outflow hydrograph shows HW & TW levels that remain below the terrain elevations below their US & DS culvert inverts for the entirety of the simulation. See with max HW/TW elevations of 648.72 and 649.04 ft respectively … And yes, that TW level begins to exceed HW level early on in the simulation.

I don’t know how RAS is translating water surface information from the 2D area to the 1D HW & TW levels for this wormhole hydrograph, but they seem to be impossible given the terrain provided. Despite this, water is successfully flowing through the culvert, although at half the rate I’d expect when compared to a previous run using a traditional culvert of the same dimensioning.

My thoughts are that either:
1) the provided HW/TW curves are incorrectly computed by the RAS output processing and the
wormhole is indeed functioning correctly,
2) or something outside of my understanding is incorrect about the model setup.

I’d love to hear your thoughts on this.

P.S. Cells surrounding the culvert are the area of concern for Courant calculations and with max velocities around 40 fps, cell sizes of 20, and a 0.5s computational timestep (also tried 0.1s) I don’t think I’m looking at a stability issue.

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