I am using COMSOL to solve a mathematical model involving thermoelectric hydrodynamic (TEMHD) flow. I am running a very large parameter sweep and using the solutions obtained to make some plots. However, I get a rather strange phenomenon appearing from time to time, in which the solution appears to exhibit strange oscillatory behaviour, and I have tried several things such as mesh refinement, reducing the relative tolerance, and changing the type of solver.

Below is one of the plots of the velocity inside an open channel as part of a parameter sweep.

enter image description here

However, the solution with neighbouring parameter values much more closely resembles this:

enter image description here

There is no mathematical reason as far as I am aware as to why this should happen, and there seems to be no regularity as to when these quirky plots arise. Even then, this only seems to happen a few percent of the time but is still rather frustrating.

Does the phenomenon I have illustrated have a name? How can it be resolved?

  • $\begingroup$ Can you add the mathematical model for the problem that you are solving? $\endgroup$
    – nicoguaro
    Aug 24 at 17:36
  • 4
    $\begingroup$ How do you know that this behavior is an artifact and not what is expected? The system could be unstable maybe (?). $\endgroup$
    – nicoguaro
    Aug 24 at 17:36
  • 3
    $\begingroup$ Additionally, you may want to specify the parameters that produce the oscillations? $\endgroup$
    – Paul
    Aug 25 at 0:25
  • 2
    $\begingroup$ Does Comsol give any error messages that might indicate that the solution didn't converge? $\endgroup$ Aug 25 at 4:23
  • $\begingroup$ @BrianBorchers Nope, not at all. $\endgroup$ Aug 26 at 11:27

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