problem when reading mesh
 

Hi everyone,


when I try to read my mesh (done with ICEM) into Fluent, I have the following message :

"Cell Centroid is xc -28.749603 yc 5.334576 zc 0.206958
WARNING: no face with given nodes. Thread 35, cell 4905"

how can I deal with it? what does it mean exactly?

Thanks for any clue...

PS: another question. Has anyone of you already had the problem that, when loading the blocks, appear thousands of blocks in any directions !!! it is not the first time for me, is it a bug from ICEM?

yorelchr

Did you use the "check mesh" utility in ICEM? For me - any error that appeared in Fluent - was shown there, too.

There are many reasons to get this problem. First check your mesh in ICEM and then take it to Fluent

As far as your last comment: Turn on and then turn off VORFN

thank you very much for your replies.
I have chechek the mesh, but I had some errors I couldn't understand, I had the possibility to put everything in a set or continue, no way to fix?
Well, I am starting again from the geometry, put away blocking and mesh.

Is it ok if one does the blocks not anly with surfaces but also points and curves, will it give me problems later? (I mean, sometimes, I don't have any surface and instead of always creating new ones, I ask ICEM to make the block an give him surfaces but also points or curves to determine where I want it).

Thanks again.

If you run the "check mesh" and an error appears, ICEM will highlight the incorrect cells. Often, you can find some problems in your blocking here. No need to remesh everything. Please post a picture of the highlighted cells and of the blocking.

Ciao Rodriguez,

I have cancelled the previous blocks...I've been "fighting" with ICEM for days and had too much files in the computer. So I've started again from geometry but I'm quite sure there will be problems when exporting into FLUENT, so I keep in mind your advice and probably I will post the "errors" tomorrow :-) ...I think I miss Gambit !!!!

Thank again

yorelchr

I know. Sometimes ICEM does strange things... Maybe I am the reason for that, but it looks more like a bug. That's when I remesh, too.
I never used Gambit, but ICEM seems to be the perfect grid generator. Just get used to it and you will like it.

well, for now, the more I use it, the more I "hate" it :-)

I'm still on the same geometry and mesh.
Is it possible to have 2 adjacent blocks with different mesh? sometimes it seems to be possible, but sometimes not. How can I know what are the situations in which it is possible?

thank you so much in advance!!!

Maybe someone has to correct me, but I think it is not possible. Two adjacent blocks have a common edge and both use the edge's parameters. Can you show a screenshot if that happes?
If you want to have such a thing (non-conformal mesh) you have to convert both blocks seperatly and merge the two meshes I think...

Also: Just upload a screenshot of your setup / blocking. You will get excellent tips from people here normally.

ok, I have put 2 screen-shots: one for the blocking, the other one for the mesh.
The number of nodes are really bad, but I'm really fed up to have to re-renter them each time (no way ICEM memorize them???) .
Well, I have problems with the upper blocks. The 2 smalls, are ok, but when I add the other one next to them, I have this strange mesh....and the mesh of the 2 small is not ok anymore.
I don't know if these pictures give an idea...
I should then do separate geometries and mesh each time I have a different mesh and merge at the end?

PS: before canceling the blocks (first I have built all the blocking but since I have problems, I've canceled them), and many times, it was ok with 2 different meshes, that's why I was wondering if it couldn't be ok under some circumstances...)

ok, I have divided the domain. For the moment, I just have something that is topologically equivalente to a cube, just one block, meshed, ok...FLUENT doesn't read the mesh !!! I think it is a problem of periodicity (there is no explanation in the error message...), but I don't understand how to solve that. How can I just cancel all periodic pair of points so I can do it from the beginning?

yorelchr: did you make the association?

I will have a closer look tomorrow, but don't you have a triangle-shaped block in the middle?

Take a look here: http://www.cfd-online.com/Forums/ans...s-meshing.html

http://www.cfd-online.com/Forums/att...sh-meshpic.jpg

But that's not what he did, right? His block looks like it has a triangular face...

Yes he did not. He need to implement quarter o-grid (or Y-grid). Also I see there is association problem too.

Looks like christine gets some homework ;)

i have a video on how to do this mesh in icem in this exact geometry... let me know if someone needs it

Thank s to all of you for your replies.
So, I will try to explain better what I'm supposed to do.
I'm working on a geometry very similar to the one posted by Far.
It's already all meshed etc...but it has too many cells so I have to reduce the domain (there would be a big part before that I put away and I will use profiles from simulations already performed on the entire domain).
I want to avoid the very thin part and for that I would like to use non-conformal mesh.
The association for periodicity have been already done by the person who did the entire geometry and mesh and I don't know how to cancel and do again.
For now, I'm working on a small part (I will merge with Fluent the different meshes) but even that small part, Fluent does not want to read it. What is wrong in my way of doing :
1. creating geometry
2. defining body
3. defining different parts, one with all points and curves
4. creating block only considering surfaces
5. meshing
6. defining boundaries

Can someone explain me the exact way to establish periodicity?
Thanks a lot

Christine

When you convert the mesh to unstructured, under edit tab run check mesh, to look for possible error

how to generate a mesh
 

Hi,I have draw a geometry in ICEM, how could I block it and generate a mesh? Could you give me your email address so that I could send you the specific question.
I am looking forward to your reply ASAP. Thanks.

Dear okko, please have a look at this thread:
http://www.cfd-online.com/Forums/ans...wers-here.html

after I draw a geometry in ICEM, how could I block it and generate a mesh? what is block used for? I am looking forward to your reply ASAP. Thanks .

thanks for your reply. Yes, I have saw the extra resourses, but I still don't know how could I block and what is the aim for block?

Hi, I can highly recommend these videos (in my link is 1/3, but you will find 2 others on youtube).
http://www.youtube.com/watch?v=tYrbScUH9RE

hello again!

I'm still fighting with ICEM...
I have a new kind of problem: my interior faces are not seen by fluent as interior but as wall. In ICEM, these interior faces are in a same part, named "INTERIOR" and for the boundary conditions, I give the "interior" conditions. But it is still not ok.
Any idea?
Thanks again.

hello everyone,

I am, of course, still "fighting" wit ICEM.
So, I've divided my domain in several parts.
I have encountered several problems:
- For creating each part, I start from the entire geometry and I delete all the parts I don't need. But when I click to have the figure centered in the screen it remains at a corner, as if there were still some remaining parts that I can't see.
- when splitting a block, very often, the common face is not seen as "interior" but "wall" by Fluent.
and, last but not least :
- one of my part consists in a cylinder but, just 1/8 of it, so, I have a triangle...How can I deal with that?

Thanks for any help and sorry to bother again !

PS: are there some good tutorials for meshing (O-grid or Y-grid). At work, I can't read video on youtube...

Hi, I will try to answer the questions I can:
1) If you change the interior faces to "interior" in fluent, I never had problems with that. What do you mean by "But it is still not ok"?
2) I sometimes have such problems, when I create new parts and put some blocks into it. I have never encountered problems. Maybe VORFN block stuff? I have no clue what they mean...
3) When splitting a block, the common face is inside the domain. There is no connection of this face to fluent, exept you create a part and put it into it. How comes you even see them in fluent?
4) Look at the link far showed in this thread and go to post No. 10:
http://www.cfd-online.com/Forums/ans...s-meshing.html
You can see how you must create the blocks for triangle shape.
5) Tell your company IT to open fucking youtube for you. It's for work not for Justin Bieber... ;)

Hi Rodriguez,

thanks a lot for your reply.
1 . So, about my "interior" problem : "it's still not ok" because when importing into fluent, these parts appear as wall and there's no way in fluent to change to interior. But I think it's ok now : when creating the block, I was taking all the sufaces, including these interior surfaces; I've just tried without selecting them, and fluent did not see them.
2. I still don't know why there seem to be some other things remaining. I very often have problems with VORFN I think because sometimes, when clicking on "pre-mesh", appear thousand of yellow blocks...
4. I will star with O-grid now, thanks for the link
5. Well, it's not about youtube, it's just that the computers where we have ANSYS installed are old and not updated...and of course, we don't have root password to update or install anything new...so I have a nice "missing plugin message" when trying to read video :-)

1) Why do you even see the VORFN blocks? I always switch them off. I have never used them at all and also don't know what they are good for.
Also: What are you doing with the surfaces, I don't get it. If you create your first block, you select a name and that's the part where all the following "child" blocks will be in. What do you mean by "I was taking all the surfaces"?

I don't know any ICEM tutorials. When I started I watched the video I linked above. That gave me a good idea about many things in ICEM. The rest I learned by miserably failing and trying again and again...

make sure the points, the curves the surfaces and the bodies are all checked, and all your part are checked too

HI Rodriguez and Diamondx,

I have watched the video (http://www.cfd-online.com/Forums/ans...s-meshing.html , post10). It's really interesting, but I don't get how the quarter O-grid "appeared".
I'm sending you a file, a part of the entire geometry, where I have this problem of figure in the corner of the window when I use the tool "fit window". I have checked the geometry in Geometry/Repair geometry, but nothing.
In this geometry, as you'll see maybe, I have sometimes the problem of many blocks appearing...I don't know where they come from, when it happens, I close ICEM and open it again. I don't use either VORFN, it's always disabled.
And Rodriguez, I use surface for creating blocks when I want the block to be juste around a part of the geometry, to delimitate...
But with all these mistakes (the file I'm sending you is not even read by FLUENT), I think I really don't get "how ICEM works". But I keep on trying.
Thanks again.

Hi,

The problem lies in part "GEOM". For some reason the info says
--------------------------------------------------------------------------
Info for part GEOM
--------------------------------------------------------------------------
Geometry Info ----
Part contains 11 curves
Part contains 39 (23 dormant) points
...
although it only has 9 curves and 6 points. I can't see the others and don't know how to let them appear.
But these quick steps worked:
Make only part "GEOM" visible, by deselecting the others. Now create a new part (right click on "Parts"). Then, chose "Create part by selection". Use "select entities" to select all the 9 lines and 6 dots. Give the new part some name and click on apply. Delete the old "GEOM" part (right click on it) and rename the new part to "GEOM". Here we go.

Hi Rodriguez,

Thanks a lot, I've cancelled all the dormant and unattached points and curves from the ICEM panel and it worked also in this way. Now it's ok for that.
But I still can't read the mesh in Fluent. I've
1. created a block
2. given the pairs of vertices for periodicity
3. associated vertices and curves
4. created a quarter O block
5. cancelled the first block
6. ran check/fix and fix inverted block
7. done the mesh
but when opening it in fluent I have :

Can you upload all the ICEM files?
Why did you need to fix something?

well, I just did it in case there could be problems because when I ran the check/fix, it didn't tell me anything...but the first time I did all that, I didn't do any check and the problem was the same, so I did all again with that check/ fix and fix
I send you all the files.

I didn't find any problem. This is not the problem of ICEM, check Fluent .

Can you read any other mesh file into Fluent (try some tutorial mesh files comes with Fluent) ?

Do you get this problem with serial fluent or parallel fluent? Are you using Linux or Windows?

try this mesh...

I get
"...
shell 2108 has node 1781 which has no twin
there are problems with the periodicity"
warnings during check mesh. Is that ok? I never did the periodic setup with ICEM. I use FLUENT for that.