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Time-dependent Heat Transfer study - strange periodicity
Posted 19 juin 2013, 04:21 UTC−4 Heat Transfer & Phase Change, Studies & Solvers Version 4.2a 1 Reply
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Dear COMSOL users,
I'm modelling a (reasonably simple) geometry in which I have a pulsed heat source with a period of 3 minutes (1 minute the source is on and 2 it is off). The geometry is a cylinder with different layers (of different materials), one of which is the heat source. All the surfaces are cooled by natural convective cooling in air and irradiation.
I've been running a quite long calculation to see how long it takes to reach the steady-state temperature, but in my results, for the temperature on the surface, I see a strange pattern: the temperature seems to fall every 2000s and then goes up again (see attached file).
Have you ever experienced it? Is it something physical or maybe something I'm doing wrong in the calculation?
Thanks for your help
I'm modelling a (reasonably simple) geometry in which I have a pulsed heat source with a period of 3 minutes (1 minute the source is on and 2 it is off). The geometry is a cylinder with different layers (of different materials), one of which is the heat source. All the surfaces are cooled by natural convective cooling in air and irradiation.
I've been running a quite long calculation to see how long it takes to reach the steady-state temperature, but in my results, for the temperature on the surface, I see a strange pattern: the temperature seems to fall every 2000s and then goes up again (see attached file).
Have you ever experienced it? Is it something physical or maybe something I'm doing wrong in the calculation?
Thanks for your help
Attachments:
1 Reply Last Post 19 juin 2013, 05:12 UTC−4
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Posted:
1 decade ago
First of all, check if your mesh size is adequate. It might help if you refine the mesh.
Adjusting the solver settings could help, as well. Try changing the tolerance factor in your solver settings to 1e-3. Also check time stepping in the time-dependent solver settings. You might need to change the steps to 'Strict' or 'Intermediate' instead of 'Free'.
Finally, what's the error range in the convergence plot?
--
Tolga
Adjusting the solver settings could help, as well. Try changing the tolerance factor in your solver settings to 1e-3. Also check time stepping in the time-dependent solver settings. You might need to change the steps to 'Strict' or 'Intermediate' instead of 'Free'.
Finally, what's the error range in the convergence plot?
--
Tolga