code_saturne User's Forum

Hello everyone,

Hope you are doing well.

I'm working on the turbo-machinery module on code saturne and I got an error as following:

** WALL DISTANCE
-------------
Min distance = 0.98407E-04 Max distance = 0.16831E+02

(Distance calculation done in 360 iterations)
*** WARNING ***
Globally, 596 problem(s) found during the face splitting
0 open cycles,
596 edges traversed twice,
0 faces split into more than max_subfaces (= 200)

=> Eventually modify joining parameters

/home/code_saturne-5.0.3/src/mesh/cs_join_update.c:3248: Fatal error.

Cannot achieve to reorient the current joined face with face 301 (selected face).


I have activate the reorient when choosing the mesh.

I don't know why. Cam someone help me about that?
Thank you so much.

All the best, Yany.

Hello,

the reorientation option is only used for mesh preprocessing. If you do not have any negative volumes at first, you do not need to change it.

Your problem is probably due to a mesh quality issue at the joining interface. Could you post a view of your mesh at this interface ?.

The older "mesh coupling" turbo machinery option may be a backup solution in case of mesh joining issues, but improving the mesh in the joining region is recommended.

Did you check older posts on this forum relative to turbomachinery and mesh joining ? You may find quite a few suggestions (though we need to to a true FAQ for this, user's help is welcome here).

Best regards,

Yvan

Yvan Fournier wrote:Hello,

the reorientation option is only used for mesh preprocessing. If you do not have any negative volumes at first, you do not need to change it.

Your problem is probably due to a mesh quality issue at the joining interface. Could you post a view of your mesh at this interface ?.

The older "mesh coupling" turbo machinery option may be a backup solution in case of mesh joining issues, but improving the mesh in the joining region is recommended.

Did you check older posts on this forum relative to turbomachinery and mesh joining ? You may find quite a few suggestions (though we need to to a true FAQ for this, user's help is welcome here).

Best regards,

Yvan

Hi Yvan，

Thank you for your reply. I rebuild the mesh and the error dispearred. So I think it's because of the bad quality of joining interface.

All the best, Yan.

Yvan Fournier wrote:Hello,

the reorientation option is only used for mesh preprocessing. If you do not have any negative volumes at first, you do not need to change it.

Your problem is probably due to a mesh quality issue at the joining interface. Could you post a view of your mesh at this interface ?.

The older "mesh coupling" turbo machinery option may be a backup solution in case of mesh joining issues, but improving the mesh in the joining region is recommended.

Did you check older posts on this forum relative to turbomachinery and mesh joining ? You may find quite a few suggestions (though we need to to a true FAQ for this, user's help is welcome here).

Best regards,

Yvan

Hello, Yvan,

Hope you are doing well.
For my case, the wind turbine, after running several steps, a new error appears......Do you have any idea about that? I decreased the time step, but it didn't work.

*** WARNING ***
Globally, 600 problem(s) found during the face splitting
0 open cycles,
600 edges traversed twice,
0 faces split into more than max_subfaces (= 200)
=> Eventually modify joining parameters
/home/code_saturne-5.0.3/src/base/cs_turbomachinery.c:787: Fatal error.

Error in turbomachinery mesh update:
Number of boundary faces has changed from 115668 to 118068.
There are probably unjoined faces, due to an insufficiently regular mesh;
adjusting mesh joining parameters might help.

The mesh is attached. Many thanks!


The mesh of rotor and stator should be connected with each other or there is a small gap between them?


All the best, Yan.

Hello,

It seems you did not post the mesh. A few views of the mesh near the joining interface might be enough if the mesh is big.

How is the rotor/stator interface meshed ? Did you use a general triangle surface mesh, or a mesh of quadrangles generated by rotational extrusion ? The second option would be better.

I any case, similar questions have been asked and answered on this forum in the last 2 or 3 years, so I recommend using the search feature of the forum for this.

You do not need to have a positive gap between parts, but ensuring you have one could lead to being able to use more aggressive joining options... which might not be such as good idea quality-wise a as cell volumes could then vary slightly from one time step to the next...

Regards,

Yvan

Yvan Fournier wrote:Hello,

It seems you did not post the mesh. A few views of the mesh near the joining interface might be enough if the mesh is big.

How is the rotor/stator interface meshed ? Did you use a general triangle surface mesh, or a mesh of quadrangles generated by rotational extrusion ? The second option would be better.

I any case, similar questions have been asked and answered on this forum in the last 2 or 3 years, so I recommend using the search feature of the forum for this.

You do not need to have a positive gap between parts, but ensuring you have one could lead to being able to use more aggressive joining options... which might not be such as good idea quality-wise a as cell volumes could then vary slightly from one time step to the next...

Regards,

Yvan

Hello Yvan,
I'm so grateful for your kind help. I searched the related key words in the forum and did what I can do for that, but the error still exist. The interface mesh is attached. Is there any problem about that?
Thank you so much.



All the best, Yany.

Hello,

Did you check the attachments ? All I see are "logo" type images.

Regards,

Yvan

Yvan Fournier wrote:Hello,

Did you check the attachments ? All I see are "logo" type images.

Regards,

Yvan

Hello Yvan,
I'm sorry that there may something wrong with the attachment. Now I upload a second time, entire mesh and the interface of rotor and stator.

There is an new error after I modified the mesh.
Error in turbomachinery mesh update:
Number of boundary faces has changed from 59700 to 59718.
There are probably unjoined faces, due to an insufficiently regular mesh;
adjusting mesh joining parameters might help.

Thank you so much.

All the best, Yany.

Hello,

Your mesh seems quite clean. The geometry might be slightly off in the normal direction, sto one face is not completely joined but leaves a small "splinter" as a boundary faces.

You may try slightly increasing the joining fraction parameter for the turbomachinery module (for example from the default of 0.1 to 0.15).

Best regards,

Yvan

Yvan Fournier wrote:Hello,

Your mesh seems quite clean. The geometry might be slightly off in the normal direction, sto one face is not completely joined but leaves a small "splinter" as a boundary faces.

You may try slightly increasing the joining fraction parameter for the turbomachinery module (for example from the default of 0.1 to 0.15).

Best regards,

Yvan

Hello Yvan,

Thank you for you reply. Actually I have change the joining fraction number to 0.15 and a higher value, but the error still exist. The rotation zone is exact round. What do you think I should do in next step? I have attach the case folder. If you have time, could you please have a look at it? Many thanks.

All the best, Yany.