Meshing Problem

Project Support
1

Hello!

I’m new to using SimScale and CAD, but I’m trying to use it for school to model the effects of straw grid formations on windbreaking. I keep running into an error, “One or more cell zones do not intersect the flow region or the intersection results in a non-solid body. Cell zones must overlap with the flow region.” and I would really appreciate if someone could help me out! I’ve been looking at other forum posts but I still can’t figure it out. It seems to maybe be an issue with my CAD, but I don’t even know where to start to fix it…

Here’s the link to my project: https://www.simscale.com/workbench/?pid=4395273073493840996&mi=spec%3A8053c377-a18c-4da7-a5e0-fe4f4b499977%2Cservice%3AMESHING%2Cstrategy%3A47&sh=50

Thanks so much!

2

Hey there!

I think you need to first delete the part representing the solid in your model. You can do this with the CAD Edit mode:

Then, I can see that you only have inlet velocity boundary condition. You will need a pressure outlet boundary condition, and also some type of wall on the other faces.

Please check of our tutorials for reference on external aerodynamics setup:

3

Hello! Thanks for the super quick response!

Do you mind further explaining what deleting the part representing the solid in the model means? I have the grid that I created in CAD, and then the larger external flow volume which I created while following the different tutorials on external aerodynamics. Which is the part representing the solid?

Also, yes thank you for the pointer on the pressure outlet and the other walls! I did miss that in the tutorial.

Thanks!

4

The solid part would be the grid, as the flow region is meant to contain the fluid.

5

So I deleted the solid grid part from the flow region, and I was able to resolve the meshing problem and actually run the program, but I’m worried that this isn’t necessarily what I’m trying to model. I was envisioning that the grid would be of a porous material through which some air would be able to flow in the x and y direction, representing rows of grass that were planted. By deleting the solid grid part from the flow region, I can no longer make the grid a porous material because the physical grid no longer exists. Do you have any suggestions about how to represent this without running into the meshing problem?

Many thanks!

6

Hey again!

I hadn’t understood the intention of the model. So you need to model this in a different way:

  • The grid should not be cut from the flow region, but intersect it.
  • I think you do not need such a large flow region.
  • You need to assign the porous media for the grid body, to let the meshing algorithm know how to resolve the intersection of the parts.

I have a question, will the grass be planted on the current grid walls, or in the inner squares?