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time step size question

Posted Nov 4, 2010, 12:38 p.m. EDT 3 Replies

Wei Wang
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In the Times edit field of the time dependent solver setting, say, range(0,0.01,1.5), the 0.01 is the time step size in the computation or the output time in the simulation? It seems it is just the output time of the result since when I changes the value from 0.0.1 to 0.1, the computation elapse time does not change for the same end time 1.5. If I want to change the time step size in the computation, what should I do?
Thanks.
3 Replies Last Post Nov 5, 2010, 9:44 a.m. EDT
Heather Dillon
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Posted: 1 decade ago Nov 4, 2010, 6:22 p.m. EDT
If you are using 4.0 there seems to be more than one place to input the time range. If you drill down inside the solver to the "time dependent solver" you can input the range directly again. Not sure if that helps.
If you are using 4.0 there seems to be more than one place to input the time range. If you drill down inside the solver to the "time dependent solver" you can input the range directly again. Not sure if that helps.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Nov 5, 2010, 8:45 a.m. EDT
Hi

I can only confirm (having burnt my finger several times, that in V4.0a the time sequence you put in the continuation step (or parameter seep) node (upper one) are not changed again in the lower depedent nodes, you must update TWICE if you do not delete and regenerate your study (but the latter will also delete all your Results settings dependet onthe study). It's slightly annoying, but once you know it, its quickly fixed.

This is much better liniked and treated in 4.1 ;)

--
Good luck
Ivar
Hi I can only confirm (having burnt my finger several times, that in V4.0a the time sequence you put in the continuation step (or parameter seep) node (upper one) are not changed again in the lower depedent nodes, you must update TWICE if you do not delete and regenerate your study (but the latter will also delete all your Results settings dependet onthe study). It's slightly annoying, but once you know it, its quickly fixed. This is much better liniked and treated in 4.1 ;) -- Good luck Ivar
Danial Tz
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Posted: 1 decade ago Nov 5, 2010, 9:44 a.m. EDT

In the Times edit field of the time dependent solver setting, say, range(0,0.01,1.5), the 0.01 is the time step size in the computation or the output time in the simulation? It seems it is just the output time of the result since when I changes the value from 0.0.1 to 0.1, the computation elapse time does not change for the same end time 1.5. If I want to change the time step size in the computation, what should I do?
Thanks.


To add a bit more:

what you saw in the first picture is "output" time, which the model will save the solution to file. However what you see on the second picture is what solver does take, and that you can restrict. Overall, the picture 1 time does restrict the second time.

Say your output time is 1s, while your maximum solver time-step is 10s. The solver will effectively use 1s as timestep. But not the other way around.


--
Comsol 4.0a
Ubuntu 10.04.1
[QUOTE] In the Times edit field of the time dependent solver setting, say, range(0,0.01,1.5), the 0.01 is the time step size in the computation or the output time in the simulation? It seems it is just the output time of the result since when I changes the value from 0.0.1 to 0.1, the computation elapse time does not change for the same end time 1.5. If I want to change the time step size in the computation, what should I do? Thanks. [/QUOTE] To add a bit more: what you saw in the first picture is "output" time, which the model will save the solution to file. However what you see on the second picture is what solver does take, and that you can restrict. Overall, the picture 1 time does restrict the second time. Say your output time is 1s, while your maximum solver time-step is 10s. The solver will effectively use 1s as timestep. But not the other way around. -- Comsol 4.0a Ubuntu 10.04.1

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