SimScale CAE Forum

Mesh generation problem


I’m trying to model mikrofluidic channels and I encountered a mesh problem. For some reason the mesh is also outside the channel. Maybe the desing it is not “water-proof” for some reason, but I can’t find the problem.

Can anyone help?

For an easy channel design the meshing with the same properties worked fine.


Hi @rwilcken. Try a parametric mesh instead of an automatic one, this way you can ensure that the ‘material point’ is within the geometry. The parametric mesh is a bit more involved, check the tutorials to get started.

If you need any further help just shout,



Thank you for the hint.

With the material point, it now puts the mesh on the inside where it belongs. But only for a part of the structure, depending on where I put the point. I couldn’t figure out how to expand the area. I just managed to crash the mesh generation for a few times.

Any ideas would be greatly appreciated.
Most important, if anyone could have a short look on the CAD drawing itself? Not that there is a problem, because I’m really not an expert in this and AutoCAD Free Trial is running out :stuck_out_tongue_winking_eye:


Hi @rwilcken, Firstly, as long as this is the desired shape I don’t think I see anything wrong with it. It is water tight. I think you simply need to increase the number of cells in each direction, consider tripling it to start. I would expect this to give better results and increase the cell count or refine locally to improve it.

Finally, I use OnShape, you may have heard of it but it is very powerful and also free to individual non-professional users ideal if you just need to put a geometry together for SimScale.

Let me know if this helped or you need any more help,

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Hi @rwilcken,

I had a second look at this. With the small geometry, visualizing the material point in the viewer becomes quite difficult.

As you can see, in the Z + direction the line denoting the plane of the material point does not fall inside the geometry (this is not supposed to happen and I will report it to our engineering team)

I corrected the coordinates of the material point:

I added a regional refinement and surface refinement. And also noticed in the solver log that many of the volumes were < 1e-13, thus I updated the min cell volume (see Operation settings) to 1e-30. See this post.

You will find the finished mesh in this project:



Thanks a lot to you two.

It is good to know, that the CAD geometry is ok. I just tried AutoCAD for the first time. OnShape also looks pretty good though. AuntoCAD is 175€ a month or somthing like this. It’s pure isanity.
Increasing the number of points worked out, too. I think I tired it yesterday and crashed the mesh generator. It’s a little confusing that it worked out know. But hey, it worked.

Thanks to Anna for going through this. A lot of really helpful new tricks. :slight_smile: