Time-Dependent Scaling of Variables

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Good morning,

I have a concern for which I hope the forum has a solution:

In time-dependent problems the variables are scaled when initializing the problem, and if wished, rescaled after consistent initialization. Especially in time-dependent problems it may happen that the magnitude of the unknown variables significantly varies with increasing time. Take for example a light arc, where temperatures after ignition may reach 10^5K, while before ignition the tmperature remains at "room-temperature". If scaling is choosen "automatic", comsol will not know anything about high temperatures in the time-domain and will probably set the scaling factor at around 300K. This factor will make convergence difficult, when attaining high temperatures. On the other hand, if the scaling factor is choosen 10^5 from the beginning on, the accuracy of the solved unknowns at the beginning of the simulation will be very poor. Is there any possibility to update the scaling factors every n-th time-step, or even, make the scaling factor dependent on the solution of previous time-step. This would make both the solution more accurate and run faster.

Thanks for any comment Ludwig

0 Replies Last Post 2024年3月25日 GMT-4 05:31
COMSOL Moderator

Hello Ludwig Herrnböck

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