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Plot of Temperatures for a Time Dependent Step
Posted 19 nov. 2012, 12:52 UTC−5 2 Replies
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Hi,
I was running a case last week that included several physics, including heat transfer. Just by chance, I looked at the computed temperatures at the end of a steady state step and again at the start of the following time dependent step. I happened to notice that the temperatures were not quite the same. So I generated the attached simple case using only one physics to see if it would happen again. It did!
The differences in temperature for the attached example case are insignificantly small, but I am very surprised that there is any difference.
Does anyone know if this is just a quark associated with how the plot temperatures are generated for a transient step?
Regards,
Joe
I was running a case last week that included several physics, including heat transfer. Just by chance, I looked at the computed temperatures at the end of a steady state step and again at the start of the following time dependent step. I happened to notice that the temperatures were not quite the same. So I generated the attached simple case using only one physics to see if it would happen again. It did!
The differences in temperature for the attached example case are insignificantly small, but I am very surprised that there is any difference.
Does anyone know if this is just a quark associated with how the plot temperatures are generated for a transient step?
Regards,
Joe
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2 Replies Last Post 20 nov. 2012, 02:37 UTC−5
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Posted:
1 decade ago
Hi Joe,
I don’t know the reason exactly but it has to do with the initial transient time step size. When you force COMSOL to use a smaller initial time step the difference in temperatures will go down or disappear. I just tried setting Initial Step = 0.001 (in the Time Dependent Solver node > Time Stepping) and it does just that.
Nagi Elabbasi
Veryst Engineering
I don’t know the reason exactly but it has to do with the initial transient time step size. When you force COMSOL to use a smaller initial time step the difference in temperatures will go down or disappear. I just tried setting Initial Step = 0.001 (in the Time Dependent Solver node > Time Stepping) and it does just that.
Nagi Elabbasi
Veryst Engineering
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Posted:
1 decade ago
Hello Nagi,
Thanks for your pointer on how to get rid of the bothersome differences.
Regards,
Joe
Thanks for your pointer on how to get rid of the bothersome differences.
Regards,
Joe