[VT_Bromley]

Hey all,

I'm trying to import a grid into FLUENT and I'm constantly getting the following two warnings:

Warning: non-positive volumes exist.

Warning: non-positive face area exist.

However when checking my grid in ICEM it does not show negative values for either of these.


To quickly explain my mesh. The bottom rectangular box is full of a solid, the middle rectangular box is air initially with a ramp labeled in red. The small rectangle at the top is a porous zone. The wall facing you in light blue is a symmetry wall. My origin (0,0,0 point) is at the bottom left corner of the "air" region.

I have checked everything in ICEM and it all seems to check out, however once it is imported into FLUENT it has the above warnings. Any ideas on where to go from here?

[hossein65]

Dear all,
I got such a problem! please help!

[Far]

locate the negative volume and remove it

[faee0]

the mesh is too bad！you must remesh it

[Far]

the mesh is too bad！you must remesh it

Well that is obvious, but it may be due to some local regions e.g. at sharp corners or topology may not be correct. Therefore it is better to locate the problem area and remove that problem. It is also better for future work on similar geometries.

[realstoneman]

dear Far
I have the same problem,when I import my mesh into Fluent ,get a warning:non-positive volumes exist.I just have learn ICEM for some weeks,and I don't konw how to locate the negetive volumes as you said above.Please help me,by the way,can I just use the"edit mesh-->smooth elements globally" to smooth the mesh?
May I have you email?

[hossein65]

I could solve my problem by coarsening the mesh . You know, using a smaller mesh size can help very much. try it!

[jeevankumarb]

Hello Michael,

The way the quality measured in fluent is different form the way it is in Fluent. For fluent at least you need minimum quality of 0.05(ICEM) but still you might face problems in convergence.
From the image it seems that your topology is very bad. You have to change the topology. Just play with the blocking and thing some topologies which can give good quality mesh. Thats how you learn and expertise ICEM.

Regards

[realstoneman]

hello，
I created a mesh by ICEM CFD,but I don't know why my grids have something wrong,the attachment is the part where I found.The vertical line with 5 nodes,but why don't they maintain horizontal and merge into the line below it?
And the second picture,you can see two lines stand together,the two problems have driven me mad!!!!
Could you help me with the problem?
Thanks very much~
PS:the model I created is symmetrical,but the other side is OK,I don't know why.

May I have your email？Mine is xufei_0322@foxmail.com I wish I could communicate with you.