Posted Tue, 12 Mar 2013 11:42:08 GMT by Søren Erbs Poulsen
Dear supporters,

I noticed during different transient simulations the following error message produced by the SAMG solver: "Time step #<timestep>: SAMG has NOT converged after <some integer> iterations with the residual <some number greater than 1E-8>".

It is the <some integer> that I fail to understand. Sometimes it's 5 and other times it's 7, 13 or some other integer. Solvers have an error criterion and a number of iterations to reduce the error below this criterion. The information that the solver has not reached the error criterion after say 5 iterations is pretty useless if it has another 25 iterations to further reduce the error. It would make sense if the error message was something like this: "Time step #<timestep>: SAMG has NOT converged after the maximum number of iterations with the residual <some number greater than 1E-8>" 

How am I supposed to interpret this error message?

Best regards and thanks in advance!
Posted Thu, 21 Mar 2013 22:16:43 GMT by
I think its referring to the "maximum number of iterations per time step" which is the outter loop of the solver, which you specify in the problem settings under numerical parameters.  But it may be related to the inner-loop iterations that are specific to the solver (go to "solver type", and click properties button).  The 1e-8 is a default value for the inner loop which may be the value in the message your seeing.  You may need to decrease this and/or add more inner-loop iterations.  The more complex models require more iterations and smaller convergence values

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