Ad Lid to XS – Solution?

[igorce]

I want to make a Stedy flow simulation through a tunnel. For that purpose I modeled the tunnel with Add Lid to XS. What should I do to get a solution like the Picture No_2? Where do I make a mistake? Why I get a solution how the water flows through the barrier?

[Anonymous]

First off, the geometry looks different. Just looking at the terrain profile ignoring the WS Profile.

Second whats the downstream boundary condition here? Mixed flow conditions?

[igorce]

Yes, the geometry is different because it is a different project, but it is not important that, i think this is the procedure for conducting a hydraulic analysis through a tunnel (I followed the tutorial).
Irrelevant how the boundary conditions are selected, they are at a enouch distance to not have affect the flow regime through the tunnel. In this case boundary conditions are (Normal depth upstream and downstream, Mixed flow analysis).
The longitudinal profile shows that the water passes through the barrier. I do not know why? (Picture No.1)
Down you can see the cross section near the start of tunnel
I THINK SOMETING IS MISSING IN THE INPUT DATA!

[Anonymous]

You need to read up on culvert hydraulics and how RAS displays results. First off everything matters for the final results. A different terrain, BC, flow etc.

Second water is NOT flowing through the lid (or what you call barrier). Water is hitting the face of the culvert (tunnel) and dipping down and is under pressurized flow. The line you are looking at that looks like it is “flowing through the barrier” has a clear label in the RAS legend…Please realize what you are saying before you say it…the energy grade line does not mean water is flowing through at that level…please look into basic hydraulic computations and head.

You need to verify that piessman slots. If you do not know what piessman slots are then look it up.

WHEN HEC-RAS is OPEN HIT F1 people!!!!!!!!

[Author]

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