Learning Forum

[MRMR]

Hello everyone

for 2 days now I'm fighting with fixing the error I get while trying to mesh my solid. The message I get is:

Or another one that Multizone is not able to mesh the solid. 

In uploaded files there should be a model I try to mesh. I tried several ways of preparing my solid to meshing process and no one helped. I tried repairing my solid with all Spaceclaim tools and also no result (inexact/split edges, simplify etc.). I use for all side faces of my model ( =walls): face meshing and size element = 5-7mm. For inlet it's size element = 0.7mm and for the whole solid multizone method and inflation with 10 layers, first layer 0,004mm and growth rate 1.5 with walls as boundaries. The strange thing for me is that when I change the element size for the wall for less than 2mm everythings works perfectly ( for 1mm - 1.99 I didnt get any problems) and that's why I thought that maybe in my solid there are some mistakes but as I wrote previously different ways of building the solid should work in this case.

I have no other ideas what can be the reason of this error and that's why I decided to ask here for help.

Thank you for taking some time to read all of this and thank you in advance for all tips.

Regards
Martin

[peteroznewman]

What release of ANSYS are you using?  I am using 2019 R2 and I got no such error when meshing this geometry.

Instead of attaching the SpaceClaim document, you could attach a Workbench Project Archive .wbpz file. That way I could see how you have setup the mesh.

An idea I have is to create Virtual Topology to cover the multiple faces with a single face. 

[MRMR]

Thank you Peter for your answer.


Version. 19.2 I uploaded Workbench .wbpz file, Face Sizing and Face Sizing 3 should be 6 and 3mm.

[peteroznewman]

Sorry for the delay in replying.

I opened your archive in 19.2 and see you have a mesh.  This model also has different geometry than the first post attachment. Somehow, you overcame the error, is that correct?

The problem I see in your mesh is the minimum orthogonal quality is 2e-2 which is too small. It would be better for it to be 0.1.  One way to control that is to slice your solid up into pieces along the length and use shared topology to connect the mesh. That way, each piece has no skewness on the slice faces.

I changed the mesh controls without slicing and now you have a minimum orthogonal quality of 0.38 which is adequate.

ANSYS 19.2 archive is attached.

[MRMR]

Thank you Peter. I knew that the weekend is coming so I hope you had a little rest from helping us.

Unfortunately it means I attached the wrong file - I'm really sorry for that, I have no idea how it happened.
Could you have a look to the right file one more time?

[peteroznewman]

Why do you have a sharp corner in your fluid domain?  I would add a blend to the green edge on each side.

All the named selections are broken in your model. Is that small rectangular face a wall or an inlet?

[MRMR]

Thank you Peter for your commitment, I appreciate it very much.


Green Edge needs to stay like it is. 
I defined inlet, outlet and wall.  Originally the wall will have different temperature so that's why it's divided in so many pieces.

[peteroznewman]

When you say, "originally" that implies that segments of the wall having different temperatures is no longer a requirement. Is that true?

[MRMR]

No, it means that in the final simulation it will be divided into pieces 25mm long like it is now and every piece will have different temperature and that's why with every next 25mm of the wall., the face need to stay cut all around the solid. Because later I want to change temperatures of this wall segments and observe what will happen.

[peteroznewman]

Create a plane at each 25 mm section and Split Body so that you get separate pieces. Then use the Workbench tab and click the Share button.

[MRMR]

Isn't it necessary to create interfaces in this case? I tried dividing a solid by planes in some other simulations but I then I decided to avoid creating interfaces when it's not a must, because I saw some little flow irregularities while calculating flow parameters in CFD-Post.

[peteroznewman]

You don't get any interfaces in FLUENT when you delete any automatically generated contacts in Meshing and all the bodies are identified as fluids.

[MRMR]

I calculate in CFX. 

[peteroznewman]

I've never used CFX.

[MRMR]

Ok, so for that conversation it will be all I think. Thank you Peter again for all your help, I will try to figure it out and if I find the solution I will write something here, maybe someone will be curious. 

Regards