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Creating a time/dependent model in Conductive Media DC Module
Posted Mar 9, 2012, 5:37 a.m. EST Low-Frequency Electromagnetics, Studies & Solvers 2 Replies
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Hello COMSOL community,
I'm working with the Conductive Media DC Module and COMSOL Version 3.5. Presently I´m trying to create a time-dependent model of a wenner-array consisting of 4 electrodes. In two of them a current is applied, changing with time. I´ve got no problems to create the model, when current is defined as a time-dependent function (e.g. I*sin(2*pi*f*t)).
But now I´d like to get this progress:
- 0 - 0.01s : current I = 1 at one electrode and -1 at the other one
- 0.01 - 0.02s : switched signs (current I = -1 at one electrode and 1 at the other one)
- 0.02 - 0.04s : current I = 0 at both electrodes
- start again
Is it possible to define a progress like that for current or do I have to split this Model into three steps and restart it after each one?
Would both models (the unsplitted and the splitted) lead to the same results?
Thank you for each hints,
Daniel
I'm working with the Conductive Media DC Module and COMSOL Version 3.5. Presently I´m trying to create a time-dependent model of a wenner-array consisting of 4 electrodes. In two of them a current is applied, changing with time. I´ve got no problems to create the model, when current is defined as a time-dependent function (e.g. I*sin(2*pi*f*t)).
But now I´d like to get this progress:
- 0 - 0.01s : current I = 1 at one electrode and -1 at the other one
- 0.01 - 0.02s : switched signs (current I = -1 at one electrode and 1 at the other one)
- 0.02 - 0.04s : current I = 0 at both electrodes
- start again
Is it possible to define a progress like that for current or do I have to split this Model into three steps and restart it after each one?
Would both models (the unsplitted and the splitted) lead to the same results?
Thank you for each hints,
Daniel
2 Replies Last Post Mar 16, 2012, 11:05 a.m. EDT
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Posted:
1 decade ago
Hi
so continue use the smoth step (Heavyside functions fs... something in 3.5 see the doc) and make a step wise turn on and off on the different current source boundaries. then use atime solver in "intermediate or strict stepping mode (not free-auromatic) to catch the transitions. It used to work, and its simpler now in v4 with the step and rect predefined functions
--
Good luck
Ivar
so continue use the smoth step (Heavyside functions fs... something in 3.5 see the doc) and make a step wise turn on and off on the different current source boundaries. then use atime solver in "intermediate or strict stepping mode (not free-auromatic) to catch the transitions. It used to work, and its simpler now in v4 with the step and rect predefined functions
--
Good luck
Ivar
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Posted:
1 decade ago
Thanks Ivar,
my model works now and current looks like I want it to look. But now there´s another problem appearing when solving the model: choosing Ground (V = 0) condition for the outer boundaries, the model gets solved without any problems. But choosing electric insulation instead, the model doesn´t converge after some time steps.
Do you have any idea how I can fix this problem? I´m using the conjugated gradients linear system solver with algebraic multigrid as preconditioner. But I also tried some of the other solvers without getting a better result.
What else could I try. Is it possible, that just the choice of some boundary conditions lead th this problem?
Thanks for any help,
Daniel
my model works now and current looks like I want it to look. But now there´s another problem appearing when solving the model: choosing Ground (V = 0) condition for the outer boundaries, the model gets solved without any problems. But choosing electric insulation instead, the model doesn´t converge after some time steps.
Do you have any idea how I can fix this problem? I´m using the conjugated gradients linear system solver with algebraic multigrid as preconditioner. But I also tried some of the other solvers without getting a better result.
What else could I try. Is it possible, that just the choice of some boundary conditions lead th this problem?
Thanks for any help,
Daniel