TELEMAC-MASCARET Forum :: Topic: Error with supercritical flow at entry. (1/1)

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TOPIC: Error with supercritical flow at entry.

Error with supercritical flow at entry. 1 week 6 days ago #44585

J1618
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Fresh Boarder
Posts: 8

Hello, I'm trying to model a model channel that we have at the lab.

I'm starting with a simple rectangular channel with a flat bottom and a steep slope. I've prescribed the discharge (555) and the depth at the upstream boundary and left it free (444) at the downstream boundary since it is a supercritical flow.

However I get this error:

DEBIMP: PROBLEM ON BOUNDARY NUMBER 2
GIVE A VELOCITY PROFILE
IN THE BOUNDARY CONDITIONS FILE
OR CHECK THE WATER DEPTHS.
OTHER POSSIBLE CAUSE:
SUPERCRITICAL ENTRY WITH FREE DEPTH
IN THIS CASE GIVE A POSITIVE DEPTH
IN THE INITIAL CONDITIONS
OR PRESCRIBE THE DEPTH AT THE ENTRANCE.

I have already prescribed the depth at the entrance, and also increased the depth along the channel, and made sure that all the nodes are wet, but I still get the same error.
If I increase the depth at the entrance enough then it runs, but I'm trying to see if I can produce the typical S2 and S3 water surface profiles, and for the prescribed depths I need at the entrance for that it produces the error.

Can anyone help me with that?
Thanks in advance.

File Attachment:

File Name: boundary3x3.cli
File Size: 67 KB

File Attachment:

File Name: geometry_0.slf
File Size: 163 KB

File Attachment:

File Name: steering_0.cas
File Size: 2 KB

File Attachment:

File Name: out.txt
File Size: 7 KB

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Error with supercritical flow at entry. 1 week 5 days ago #44590

pham OFFLINE Administrator Posts: 1455 Thank you received: 560	Hello, If you prescribe elevation at a boundary, the 1st idea for initial condition is to set it at the prescribed elevation. Moreover, it is a good idea to prescribe an elevation at boundary higher the the bottom elevation. With your input files, the bottom elevation at boundary 2 is 0.12 m whereas you prescribe a 0.04 m elevation at this boundary. Quite hard to do. Hope this helps, Chi-Tuan
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Error with supercritical flow at entry. 1 week 5 days ago #44594

J1618 OFFLINE Fresh Boarder Posts: 8	Hi Chi-Tuan, Thank you for your quick response, your suggestion solved the issue , I was mixing up depth and elevation, now I get the profiles I was expecting. Thanks again, Jonathan.
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