What is the "omega" value in the residuals convergence plot?

Project Support
1

So in this project after 889/1000 iterations the run failed. when i look at the post procesing it seems to be fine until about 800iterations when the omega value in the residuals convergence plot starts oscilating and eventually skyrockets. My questions are:
1: why did it diverge? is it a bad cad model or did i do smth wrong or what?
2: what is the omega value and what does it mean?
3: how do i fix this divergence issue?

thanks a lot for your help in advance
best regards
Philippe

Link to my Project: https://www.simscale.com/workbench/?pid=4739750593988335221&rru=0a31cd8e-8bc0-4e37-baf4-972955688769&ci=9f75e692-2d35-4105-8450-18f4e1137cc9&ct=CONVERGENCE_PLOT&mt=SIMULATION_RESULT

2

Hi there,
Thank you for reaching out to us on the Forum :slight_smile:
I will have a look at the project and get back to you soon.

3

Hi there,

  1. The solution diverged. I recommend you to create a probe point at the location (7.693 m, 0.6108 m, -0.2247 m) and check the mesh.
  2. Omega in Turbulence models refer to as specific dissipation rate. You can read more about Turbulence Models here.
  3. Whenever a parameter reaches unphysical levels in the domain, the simulation automatically stops with an error message which specifies which parameter diverged and also the exact location in the model.
  • Create a Probe point result control and input the coordinates displayed in the error message. In doing so, you will see exactly where the divergence occurred
  • If the point is close to one of the boundaries, double-check all boundary conditions, making sure they are correct
  • If the point is located inside the domain, inspect the mesh around the area. The mesh quality visualization feature is very useful in this step. Even just a few bad quality cells can create instabilities in the simulation, ultimately leading to divergence
  • If you do have bad cells, make sure to inspect the CAD model around the problematic region. Look for very small faces, very detailed topology, and small gaps. These can sometimes cause poor mesh quality.

You can also have a look at this article about Divergence to understand more.

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