Divergence detected in AMG solver: ads-0

Hey everyone,

I recently made a UDF for the velocity inlet to implement an external flow problem. I compiled the UDF using the in-built compiler of FLUENT 2020R2 and hooked the UDF to the inlet. However, when I initialized the solution , FLUENT gives me this ,"Divergence detected in AMG solver: ads-0" with an error of floating point exception. I know this means something like dividing by 0 but why is this happening? I tried with a constant velocity instead of my UDF and it works fine. No errors. So I don't think the error is from the mesh. Checked my orthogonal quality and skewness. Minimum quality of 0.15 which I thought was acceptable. However, I'm still very much new to this and this is my first time implementing UDF's so any help is appreciated a lot.

Thanks :)


  • Hello,

    What is the UDF doing? Can you give us some specifics on the velocity inlet you are attempting to implement?

    Did you see any errors when you compiled and hooked the UDF?

    Quick tip - if it is an analytical expression, perhaps try using the Fluent Expressions directly (instead of a UDF) and see if this resolves your issue.

    Also, how are you initializing the solution? What values are you using?


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