SimScale CAE Forum

Solution Diverged - Bad Elements

Hi, I’m working on a CFD simulation of a toilet cubicle:

https://www.simscale.com/workbench/?pid=897259384311416241&mi=run%3A3%2Csimulation%3A3&mt=SIMULATION_RUN

However, I got the error: The solution diverged, most likely due to presence of bad elements in the mesh. Such elements tend to exist near walls and sharp corners. But I am unable to locate the bad elements in the mesh. If you could help me with this, I would greatly appreciate it!

Thank you!

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Hi @kqian_ling,

This is most likely the region that is causing trouble:

image

Zooming up in that region, you have very sharp corners:

One easy way to solve this is by adjusting the enclosure dimensions.

/Ric

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Appreciate the help :slight_smile:

I’ve tried to introduce passive species as well but an error seems to occur every time I run a simulation. The error message simply shows: An error occurred. Thus, I do not know exactly what went wrong.

I intend to simulate contaminant particles arising from the toilet bowl, and want to observe how the exhaust outlets remove these contaminants. Could you help me with this?

Hey again!

Yes, most definitely. Your simulations are being cancelled because they are diverging (check the residuals plot).

So I see that you are still using the same mesh as before. Try adjusting the enclosure of your domain to get rid of that sharp corner on the bottom of the toilet. Giving 20 centimeters of room in that area will not change your results dramatically and will improve the simulation stability by a great deal.

As for the passive scalar transport, there are various approaches you can take. please read through the passive scalar documentation and the passive scalar sources documentation to have a good overview of your options. Let us know if you need more help :grin:

/Ric

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