To help users identify and troubleshoot divergence in their simulations, SimScale has a divergence monitor. The following parameters are tracked: velocity, pressure, density, and temperature. Whenever a parameter reaches unrealistic levels in the domain, the simulation automatically stops with an error message:
The error message specifies which parameter diverged and also the exact location in the model. This information is valuable, and can be a starting point for the troubleshooting process.
To gain more insight into the causes of divergence, the following basic steps are useful:
- 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 want to learn more, and have a look at some trouble-shooting examples too, make sure to read this article: