Ivar KJELBERG
COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted:
1 decade ago
30 mag 2011, 01:59 GMT-4
Hi
have you check that you initial conditions are OK ? hit the "Study ... Dependent variables", right-click "Compute to Selected" anc check the coherence of all initial values
What puzzles me is that your mod1_P_g is flagged Solved for this field "UNCHECKED", and it's greyed, so COMSOL is not accepting to solve for all physics, this could lead to NaNs, but why ?
Have you tried to use a segregated solver, rather than the direct one. Your model is too complex for me to "take it in 5 min" my ususal time limit here on the Forum ;) (My boss have given me many studies for today too )
This was as seen from v4.2 (I have uninstalled the older ones)
--
Good luck
Ivar
Hi
have you check that you initial conditions are OK ? hit the "Study ... Dependent variables", right-click "Compute to Selected" anc check the coherence of all initial values
What puzzles me is that your mod1_P_g is flagged Solved for this field "UNCHECKED", and it's greyed, so COMSOL is not accepting to solve for all physics, this could lead to NaNs, but why ?
Have you tried to use a segregated solver, rather than the direct one. Your model is too complex for me to "take it in 5 min" my ususal time limit here on the Forum ;) (My boss have given me many studies for today too )
This was as seen from v4.2 (I have uninstalled the older ones)
--
Good luck
Ivar
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Posted:
1 decade ago
30 mag 2011, 10:57 GMT-4
Hi Ivar,
Thank you so much for your time and suggestions.
I took a look at the initial values and the mod1.P_g has zeros everywhere initially, which does not make sense. I have specified it to be the atmospheric pressure. Do you know why and how I could modify this?
"What puzzles me is that your mod1_P_g is flagged Solved for this field "UNCHECKED", and it's greyed, so COMSOL is not accepting to solve for all physics, this could lead to NaNs, but why ?"
--I don't quite get this. Could you please explain a little bit? Thank you so much!
I will check out segregated solvers.
Thanks a lot again. Really appreciate it.
Haolin
Hi Ivar,
Thank you so much for your time and suggestions.
I took a look at the initial values and the mod1.P_g has zeros everywhere initially, which does not make sense. I have specified it to be the atmospheric pressure. Do you know why and how I could modify this?
"What puzzles me is that your mod1_P_g is flagged Solved for this field "UNCHECKED", and it's greyed, so COMSOL is not accepting to solve for all physics, this could lead to NaNs, but why ?"
--I don't quite get this. Could you please explain a little bit? Thank you so much!
I will check out segregated solvers.
Thanks a lot again. Really appreciate it.
Haolin
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Posted:
1 decade ago
30 mag 2011, 14:38 GMT-4
Hi Ivar,
And when I used the segregated solver, another error was given:
Recoverable error in residual, but solver could not recover.
Time : 0.0005509748135944119
Last time step is not converged.
I searched this forum and online but had no luck what this means.....
Your help is greatly appreciated.
Best,
Haolin
Hi Ivar,
And when I used the segregated solver, another error was given:
Recoverable error in residual, but solver could not recover.
Time : 0.0005509748135944119
Last time step is not converged.
I searched this forum and online but had no luck what this means.....
Your help is greatly appreciated.
Best,
Haolin
Ivar KJELBERG
COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
31 mag 2011, 01:14 GMT-4
Hi
for me it remains linked to an "ill conditioned matrix" = BCs that are not sufficiently independent or missing or initial values too far off from expected results.
Perhaps you can start with the model somewhat simplified, run a first time, use the results as initial conditions, or as a linear interpolation of the initial conditions. With pressure ayou have also the relative "gauge" pressure and the absolute pressure" thta might play you a game. Finally many of the material properties are T and p dependent, which makes the simulations non-linear, even if they are often just as "correct" if you used constant values for the material properties
--
Good luck
Ivar
Hi
for me it remains linked to an "ill conditioned matrix" = BCs that are not sufficiently independent or missing or initial values too far off from expected results.
Perhaps you can start with the model somewhat simplified, run a first time, use the results as initial conditions, or as a linear interpolation of the initial conditions. With pressure ayou have also the relative "gauge" pressure and the absolute pressure" thta might play you a game. Finally many of the material properties are T and p dependent, which makes the simulations non-linear, even if they are often just as "correct" if you used constant values for the material properties
--
Good luck
Ivar
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Posted:
1 decade ago
6 set 2012, 10:50 GMT-4
Hi,
Was this issue solved? I have downloaded the model you put here to try and learn from it. If you have one, can you contact me and send me the model? I'm having trouble with coupling physics in *my* model.
My E-mail is Shovalwarman@gmail.com
thank you very much,
Shoval
Hi,
Was this issue solved? I have downloaded the model you put here to try and learn from it. If you have one, can you contact me and send me the model? I'm having trouble with coupling physics in *my* model.
My E-mail is Shovalwarman@gmail.com
thank you very much,
Shoval