I have been trying to simulate heat transfer problem in Comsol 5.5 for long time but it always throw an error stating:
"Failed to find a solution.
Maximum number of Newton iterations reached.
There was an error message from the linear solver.
The relative error (0.31) is greater than the relative tolerance.
Returned solution is not converged.
Not all parameter steps returned".
please help if anyone has fixed this type of error earlier.
Dear Shivendra Patel,
please add some details about your model. I can see that you are performing two steps in the same study, one time dependent and one stationary. What are you trying to simulate? Have you tried to perform the study with just the first step?
It is not so problem. Your problem may be solved by one of the followings:
1- Rebuild the mesh by considering finer mesh (or in some cases coarser one).
2- If your problem is time dependent, you can reduce the time step.
3- The initial values of variables (temperature) can also contribute in reaching the convergence faster.
4- The nature of the parameters of the problem also affect the convergence.
5- If your problem include convective heat transfer, you may check the connection between the the fluid flow and heat transfer physics.
Dear Shivendra Patel
as suggested in the first answer, it would be very helpful if you could provide more information about the model, such as initial conditions, boundary conditions, etc.
The first 3 suggestions of the second answer should be also of help. In addition to point 3, I would suggest checking the COMSOL blog where a lot of information about ramping of nonlinearities for improved convergency are presented, such as this one:
https://www.comsol.com/blogs/nonlinearity-ramping-improving-convergence-nonlinear-problems/
Furthermore, depending on the problem, it can just be that you have allowed too few iterations for the nonlinear solver, so try also to increase the maximum number of Newton iterations.
Best of luck,
Antoni Artinov
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