# what does "Solution Convergence" actually mean?

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 November 11, 2015, 13:34 what does "Solution Convergence" actually mean? #1 New Member   Prince Abraham Join Date: Oct 2015 Location: Kovilpatti Posts: 5 Rep Power: 10 I am new to fluent. I am working in PEMFC module. I can't understand the actual meaning of convergence of solution. Many says, its the balance of the energy, momentum etc., But i'm still not clear about that. A converged solution will have correct geometry, material zones, boundary conditions and all other parameters? & a A solution which doesn't converged, will have Incorrect geometry, material zones, boundary conditions and all other parameters? On which it depends? tianjunjie likes this.

 November 12, 2015, 00:56 #2 Senior Member   Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,665 Rep Power: 65 Convergence is defined purely based on the solution value and nothing to do with balances or anything else. Convergence is not a measure of accuracy. It's helpful to review some basic calculus of sequences & series. As you iterate from one iteration to the next, the solution values forms a sequence. You like to stop iterating when the solution has converged. For example this sequence converges to 1. 0.9000 0.9900 0.9990 0.9999 1.0000 1.0000 1.0000 1.0000 1.0000 Now if the actual solution is 2, then my sequence converges to an incorrect result but it converges nonetheless. Now replace my sequence of numbers with solution values (local x-velocities, y-velocities, z-velocities, pressure, temperature, etc) but only their values. A good solution will of course be converged and be accurate, but those are two different concepts. You must check for accuracy separately from convergence. Once you have determined whether or not your solution is converged, then you can check for balances, etc and judge whether your solution is of reasonably quality. hulli and daku like this.

November 12, 2015, 11:08
convergence graph
#3
New Member

Prince Abraham
Join Date: Oct 2015
Location: Kovilpatti
Posts: 5
Rep Power: 10
Thank you so much Lucky Tran..

What can we infer from the convergence graph?
Please see the attached graph, the profiles are repeating again and again!

What can we infer from it?
Attached Images
 graph.PNG (24.3 KB, 131 views)

 August 3, 2018, 16:35 #4 Member   Soumitra Vadnerkar Join Date: Aug 2018 Posts: 70 Rep Power: 7 Thank You. I had the same question

 February 2, 2022, 11:44 #5 New Member   Mahima Pareek Join Date: Feb 2022 Location: Pune, India Posts: 4 Rep Power: 4 I had the same question, could someone check in one the image that has been sent and tell us what to infer?

 February 2, 2022, 17:08 #6 Senior Member   Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,665 Rep Power: 65 If all you have is a residual plot, I can infer that you haven't actually checked any solution values

 Tags fluent 14.5, pemfc module, solution converged