[ms42]

Hi everyone,

This is my first time posting on this forum, though I've made good use of its archives for the past few weeks. I'm currently trying to model this years formula car for my school's FSAE team in StarCCM+.

I've followed this tutorial, https://www.youtube.com/watch?v=I0beXgSOijY , almost verbatim up to the 4th video, mesh generation. The car model is one part, imported as a step file.

When trying to generate the mesh, I get an error that says the geometry is self-intersecting.

I tried meshing the car body by itself and it gave the error, so I'm assuming the issue is with the car. However, I have tried a number of things to correct this. I found 4 pierced faces with surface repair and fixed them so now it shows 0 pierced faces. I tried surface wrapping the car model with a very small base size, using the automated mesh function with a very small base size, and moving the flow domain away from the model so it won't intersect in any manner, despite the model needing to intersect the domain at the tires.

Is there anything I'm missing that could cause a self intersection and not be shown in the surface repair screen?

Any help would be greatly appreciated. Thanks!

[ggulgulia]

Hey

Did you run a surface repair check on your model? how many regions/parts and mesh models have you got on the cad model? I will also suggest to enable per-region meshing if you are doing regions based meshing.

Try watching the videos on surface repair online. This is a very important skill for all ccm+ users

[ms42]

Originally Posted by ggulgulia

Hey

Did you run a surface repair check on your model? how many regions/parts and mesh models have you got on the cad model? I will also suggest to enable per-region meshing if you are doing regions based meshing.

Try watching the videos on surface repair online. This is a very important skill for all ccm+ users

I used the surface repair tool that checks for 7 different types of problems. I fixed all of the pierced faces/self intersecting geometries. I've run the mesher with automatic surface repair and it doesn't help.

I only have one region for the car to find total downforce and drag, one for the ground, one for each of the side walls of the flow domain (symmetry planes for half car model), one for inlet, one for outlet, one for the top of the flow domain that i left unlabeled.
I set it to per-part meshing, but i didn't see a per-region mesh options. What does that do?

I watched the surface repair video in that tutorial set, but I will find others.

Thank you for your response!

[ggulgulia]

the only parameters you MUST repair during surface repair is Pierced Faces, Free Edges, Manifold Vertices and Manifold Edges. If these 5 parameters are zero then how can there be any free edges?

Are you using region based meshing? How many regions and mesh continua you have? If you are applying same mesh continua for multiple regions, you must enable Per-Region Meshing in the particular mesh model.

[ms42]

Originally Posted by ggulgulia

the only parameters you MUST repair during surface repair is Pierced Faces, Free Edges, Manifold Vertices and Manifold Edges. If these 5 parameters are zero then how can there be any free edges?

Are you using region based meshing? How many regions and mesh continua you have? If you are applying same mesh continua for multiple regions, you must enable Per-Region Meshing in the particular mesh model.

Now you understand my confusion haha. I fixed all of the pierced faces and I never got an error for a non-manifold part.

I believe I used part based meshing. I selected the domain with the car subtracted from it and used the automated meshing tool with surface remesher, trimmed cell mesher, and prism layer mesher. Should I look up region based meshing and try that? Are there advantages to one or the other?

[ggulgulia]

Hi

If you have multiple parts and one mesh continua for all parts, then you must enable per-part meshing. Disable automated correction, it tends to move vertices, sometimes in unwanted positions and directions..

[ms42]

Originally Posted by ggulgulia

Hi

If you have multiple parts and one mesh continua for all parts, then you must enable per-part meshing. Disable automated correction, it tends to move vertices, sometimes in unwanted positions and directions..

I've tried region based and part based meshing, I believe. I got it to work for a few models earlier, but once I added a fin to the solidworks model and tried to run it again, it started giving me the same self-intersecting geometry errors despite having no pierced faces.

I did have an issue with the symmetry plane that cuts the center of the car. It had a lot of difficulty meshing some curves against the symmetry plane.