Velocity and depth plot show zero through culvert barrel

[Anonymous]

2D HEC-RAS 5.0.6 RAS Mapper question about culvert profile lines:

I have a culvert running through an embankment and it appears to be passing flow well (flow plots and particle tracing make sense). However, the depth and velocity in the barrel is zero where it passes through the embankment.

Is this an error in how it’s plotting or is there something fundamental wrong with the culvert? The barrel is going through a weir that follows the shape of the embankment terrain profile. It’s important for me to know the resulting velocity at the outfall, so I want to make sure there’s nothing suspect going on inside the culvert.

Thanks!

[Anonymous]

RAS Mapper does not plot the depth and velocity inside of a culvert only the overland flow. For instance, if you had a culvert crossing where the road was also being over topped, the flow and velocity you would see would be from the over topping flow.

As far as I know, for culverts inside of a 2D area RAS does not output the depths and velocities. It would be nice if they added more detailed output.

It would be a little awkward, but if you want to investigate the velocities, after you have made your 2D run:

You could create a small 1D model of the culvert and use the downstream water surface and flows to get more detailed answers. If the culvert inlet and outlet are inside of a single cell, this should be pretty straight forward. If the inlet or outlet span multiple cells, it will be a little harder to figure out the resulting water surfaces.

[Anonymous]

Good to know, thank you for the swift reply!

I really just wanted to make sure I was actually capturing the flow. I need to know the velocity in the cell at the outfall to calculate the Richardson number for stratification. Hopefully a profile just downstream from the culvert’s exit will be accurate enough for this.

I appreciate the insight.

[Author]

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