Greetings! It is time once again for another deposit of our COMSOL Tips & Tricks. This month, our Josh Thomas provides input on the "Results while solving" function. As always, we are interested in hearing your feedback and answering questions that arise in your continued use of
COMSOL.
Most COMSOL users probably know that you can track your results during a solution process by using the "Results while solving" function. But, did you know that you can actually use this feature to track non-converged results during any non-linear or segregated iterations? This is the difference between setting "Results
while solving" on the Step-level (which is what you are probably used to) versus setting this on the Fully-coupled/Segregated-level. Setting "Results while solving" on the Step-level will post results as soon as converged results are available; for example, at each completed time step or at a completed parameter step when running a parametric sweep. In contrast, setting "Results while solving" on the Fully-coupled/Segregated level gives the current results at the
completion of each non-linear iteration or each Segregated iteration. These results are NOT converged until the last iteration is reported, but these results could be used to track progress of the solver process. This information should be used in conjunction with the Convergence error plots that show up by default.
The
following plots show the approximate error at each non-linear iteration (the normal convergence plot you are used to) and a probe plot of the velocity at a point at each non-linear iteration. Only the final velocity is the correct one, but being able to monitor how your solution field is changing with each non-linear iteration may be helpful in cases where you need to troubleshoot non-convergence.
