open TELEMAC-MASCARET The mathematically superior suite of solvers

Hi everyone

I took a mesh from a model which was working fine and redid it with a new density shape, to have bigger meshes in some parts. No other parameter was changed. Opening it in FUDAA was ok.

When I tried to run the new model, I got the following error : GEOELT: ELEMENT 89140 : DETERMINANT NEGATIF. I checked element 89140 and it's in an unchanged area of my mesh (far away from my new density zone, not even on the outline), so I don't see why this element would crash the computation.

A forum search led me to Sarah F’s post about that same error (reply was it was a precision problem) but it was after she imported a *.2dm mesh in BlueKenue, not creating one from scratch in BK. Plus my mesh in that area is 15m wide and again, not changed from the previous one.

Does anybody have any ideas about that very error ? I put the error message below.
Any help would be greatly appreciated.

Thanks


READGEO1 : TITRE= newSelafin

NOMBRE D'ELEMENTS: 89169
NOMBRE REEL DE POINTS: 44787
MXPTEL (BIEF) : NOMBRE MAXIMUM D'ELEMENTS VOISINS D'UN POINT : 10
NOMBRE MAXIMUM DE POINTS VOISINS D'UNPOINT : 11
SEGBOR (BIEF) : NOMBRE DE SEGMENTS DE BORD = 403
EN COMPTANT CEUX DUS A LA DECOMPOSITION DE DOMAINE
CORRXY (BIEF) : PAS DE MODIFICATION DES COORDONNEES

MAILLAGE : MESH ALLOUE

****************************************
* FIN DE L'ALLOCATION DE LA MEMOIRE : *
****************************************

INBIEF (BIEF) : MACHINE NON VECTORIELLE (SELON VOS DONNEES)
GEOELT: ELEMENT 89140 : DETERMINANT NEGATIF
unable to read the cmd header on the pmi context, Error = -1
.
Error posting readv, Une connexion existante a dû être fermée par l'hôte distant.(10054)
unable to read the cmd header on the pmi context, Error = -1
.

job aborted:
rank: node: exit code[: error message]

Hello,

Telemac requires counter-clockwise oriented elements, but I think Blue Kenue can check and correct orientation. I would be interested in getting the whole files, so that I can run the case and try to do an automatic re-orientation of the element in the next version, that would solve the matter once for all.

Regards,

Jean-Michel Hervouet

"Edit->T3 Mesh->Make All Elements CCW" is the function to use for this.

Cheers... Martin

Hello,

Im just starting with TELEMAC2D and i dont know a lot of thing, so i hope you can help me with one thing .

I dont know how to fix the problem with the mesh (see image - negative determinant). Also send files.


Thanks

Hi

You build a wrong mesh so you should solve this before trying to run telemac.
the main problem is located here:



But you have also probably some other problem with the boundary nodes which sometimes have more than 10 neighbors.
You should refine your boundary.

Regards

Your use of the channel mesher in this case is not appropriate.
The intention of the channel mesher is to create regions of elements elongated and aligned with a channel.

At the density you have specified you will have better results by forcing the channel edges with hard or soft constraint lines in the regular mesher. Note: the constraint lines should not be too close to the mesh boundary so you should probably extend the domain a bit to the north and to the east.

It also looks like you turned off the "Resample outline" switch. I suggest you let your density object control the outline node spacing.

Hope this helps... Martin