Unable to see the element number for the negative determinant

System Modules TELEMAC-2D
1

Hello,

Im trying to simulate a dam breach along a river. I was able to get it to run and work how I wanted to with a rough mesh of 3m. However, when I make the fine smaller to get better results (1m) I am getting the error "Negative determinant. In the telemac console the error shown as follows: “GEOELT: ELEMENT ****** : NEGATIVE DETERMINANT”. I have read the other posts about the Negative determinants. I have analysed my mesh and did not find any elements with 0 area or clockwise elements.

Any suggestions as on what might be wrong with the mesh or the setup of the telemac files.

PS: I have attached the relevant files

Leimbach_nth-2.cas (3.34 KB)
DGM_Leimbach.cli (749 KB)

2

No files :expressionless:

Fine mesh means more precision…

Did you make you analysis on the slf file?

Sometimes rounding truncation could leads to this problem

Hope this helps

3

Sorry for the lack of files, i get an error that the size of files is too large even though it is under 100mb. I’m try to upload them ASAP.

yes, in the cas file i did use the analyse mesh option but there was no information provided.

I’ll check the truncation. Thank you for the suggestion.

EDIT: The slf file is 200mb and too large to be uploaded and I get the same error message when I try to uplaod the ZIP file (67Mb). Idk if this would help, but im attaching the ss of the mesh analysis from BK

Screenshot2025-12-16115829.png
Screenshot2025-12-16115829.png1070×959 20.3 KB

Screenshot2025-12-16122106.png
Screenshot2025-12-16122106.png816×1200 108 KB

4

probabily the IELEM with negative det has a value larger than 999999:

in sources\utils\bief\geoelt.f

...

        IF(DET.LT.1.D-20) THEN

          WRITE(LU,99) IELEM

99        FORMAT(1X,'GEOELT: ELEMENT ',1I6,' : NEGATIVE DETERMINANT')

          CALL PLANTE(1)

          STOP

        ENDIF



...

just change 1I6 to 1I9 in line “99” and recompile. You will see the element number with DET.LT.1.D-20.

5

Hello [name removed],

FYI your suggestion was pushed to main and will be available in next release.

Thanks for helping users.

[name removed]