SimScale CAE Forum

Step-by-Step Tutorial: Homework of Session 4


#216

After the operation 1 is completed the interface changes to volume sets (when i set up the mesh it was on face sets, else i dont think i could’ve selected the newly created face sets)


#217

Yes I am aware of that. The difference is when the filter is set up face sets, you get matched names in the marked regions:

When the filter is set up volume sets, the names in marked regions don’t match:


#218

The thing is that i believe the filter is set up, I’m able to see and select the newly created face sets for each mesh refinement just like you, but after the operation is done I get the unmatched names.
Could you try to run the operation to see if your results are different.


#219

You are right. This is concerning. Come back to you later.


#220

Ok. Thank you for your time


#221

Greetings @Akrem,

I think that he problem with my simulation is starting with the mesh, I get this error in the Mesh Operation Event Log when the mesh operation is finished:

Then when I try to run the simulation the following error appears after 16 minutes:

What could be wrong with my mesh?, here is a link to my project:
https://www.simscale.com/workbench?publiclink=911569b8-bc4d-4835-b00a-582251211e25

Best Regards.


#222

Hi

To be honest, I have little experience dealing with stp/iges. I would always work with a clean stl file in ASCII, and never had problems with patch name mismatch, so never encountered the problem you are having.

Could you try importing a front wing in stl and in ASCII? The STL file should look like:

solid frontWing
.
.
.
.
endSolid frontWing

Just make the entire wing one patch for now. Go to CAD, export the entire wing in stl and in ASCII. Open the .stl file in a text editor and change the first and last lines to what I have demonstrated.


#223

Working with NX10 I didnt found how to export the entire wing as one. Maybe if I try Autodesk Inventor is possible, but when i upload a stl file from inventor to SimScale i get the error: “Error during uploading file FW1.stl: HTTP 500 Internal Server Error”


#224

That’s fine. I just edited it for you https://www.simscale.com/workbench/?pid=4254705844194074734#tab_0-0


#225

Right so should i make a copy of the project and try to mesh/simulate the “frontWing” instead of the “FW0501NoOverlapping”?


#226

Yes and no copy needed.


#227

It says view only, make a copyto edit on top left


#228

Hi @dylan,

I have followed the procedure that you have recommended (exporting the FW as a single ASCII .STL file), but I get the following error in the mesh log:

“Illegal triangles were found after surface tesselation. There could be a problem with the CAD geometry. / The tesselated surface is not closed. There could be a problem with the CAD geometry (such as self-intersections).”

And then the mesh quality check fails. Could you take a look in my project? I would be really pleased, since I am not able to find out what is going wrong.

https://www.simscale.com/workbench?publiclink=2ec43a9b-f5dc-4153-b0d1-c21e39847417

PD. Just in case it is relevant: I merged my FW .STL and the SimScale car .STL by means of the merger provided above, not editing the text.


#229

Problem solved.

Remember, the stl file should have this format:

solid name1
.
.
.
endSolid name1
solid name2
.
.
.
endSolid name2

If there is only one patch:

solid name1
.
.
.
endSolid name1

#230

Hi I’m not an expert but Illegal triangles are present on the rest of the car as well.
I tested only the car without FW and got the same warning, so dont think that is the problem of your mesh.
Only car project in case you want to have a look: https://www.simscale.com/workbench?publiclink=20ca1199-6544-4074-9144-6afd83e63650


#231

Hi

Your stl file starts with ‘solid CFD front wing (coords 1 and 2) WELL LOCATED (TRY6) - And half removed’, and ends with ‘endsolid Fronttirecp’. Since there is one patch, the two names should match. Also, avoid space in a file name ‘CFD front wing (coords 1 and 2) WELL LOCATED (TRY6) - And half removed’.


#232

Thank you! But in that case, the mesh eventually passes the quality check, doesn’t, it? And then you can perform the simulation. Therefore I understand that the key problem is not related to that warnings that appear in the mesh log…


#233

Guys, if the stl files follow the correct naming convention I have demonstrated, your car will be meshed properly. My mesh log says…

Checking final mesh ...
Checking faces in error :
non-orthogonality > 70 degrees : 0
faces with face pyramid volume < 1e-13 : 0
faces with concavity > 80 degrees : 0
faces with skewness > 4 (internal) or 20 (boundary) : 0
faces with interpolation weights (0..1) < 0.02 : 0
faces with volume ratio of neighbour cells < 0.01 : 0
faces with face twist < 0.01 : 0
faces on cells with determinant < 0.001 : 0
Finished meshing without any errors
Finished meshing in = 79.67 s.
End
Finalising parallel run

Whereas most of the failed meshes come with:

Checking final mesh ...
Checking faces in error :
non-orthogonality > 75 degrees : 510
faces with face pyramid volume < 1e-13 : 221
faces with concavity > 80 degrees : 190
faces with skewness > 4 (internal) or 20 (boundary) : 0
faces with interpolation weights (0..1) < 0.01 : 1
faces with volume ratio of neighbour cells < 0.0075 : 13
faces with face twist < 0.005 : 532
faces on cells with determinant < 0.005 : 33
Finished meshing with 1500 illegal faces (concave, zero area or negative cell pyramid volume)
Finished meshing in = 694.53 s.
End
Finalising parallel run

#234

No, your mesh hasnt past quality check. It contains zero/negative volume cells. Please follow the naming convention I have demonstrated for ASCII STL’s. The reason is simple: SnappyHexMesh read ASCII STL’s in that format.


#235

Ok, thank you so much. I think the problem was that I was using the merger (I thought it just did automatically all properly).