SimScale CAE Forum

Velocity field is diverging at a point

I am attempting to simulate fluid flow over a formula one car and have gotten the following error message: Velocity field started diverging. Please check the mesh quality near the reported location and try refining the mesh. If the problem occurred near a boundary, please check the boundary conditions.

It seems that I’m having an issue below my left front tire. I want to know if anyone could help me solve this issue within the Simscale program.

Here is a link to my project:


Whenever you have a diverging simulation, it’s always a good idea to go through the steps in this article. The troubleshooting steps are always the same for every single project.

In any case, if we check the mesh quality (troubleshooting step number 3 in the article), we have some very bad elements in the domain:

As you pointed out, the divergence was below the tire. It turns out that we have a gap that closes asymptotically between the tire and the bounding box of the enclosure:

This is an issue, because the gap gets smaller and smaller, which results in the boundary layers breaking, very tiny cells being generated, which ultimately causes the mesh quality to be very poor. To solve this, you can either:

  • Define a small gap between the enclosure and the tire (e.g. 2-3 cm should work)
  • Have the enclosure intersect with the tire (i.e. make the enclosure shorter), so the small gap is gone
  • Use some small pads for the tires, which is a quite common approach. Again, the idea is to prevent these asymptotic gaps from being generated.


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