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Variable time stepping

Posted Mar 8, 2012, 4:30 a.m. EST Studies & Solvers Version 4.3a 3 Replies

Tesfaye Tadesse Molla
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Hi

Would you help/suggest me on how to set up a variable time stepping scheme in a time dependent solver ( COMSOL 4.2a)

Thanking you in advance
3 Replies Last Post Nov 6, 2014, 8:21 p.m. EST
Wiktor Stenström
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Posted: 1 decade ago Mar 8, 2012, 4:45 a.m. EST
Hi Tesfaye,

I assume you use a "Time Dependent" study/solver and want to use a variable step size. COMSOL automatically determines (and varies) the needed time step to meet your prescribed tolerances. What you can control is the maximum allowed size of the time step and also whether the steps should be free (where the solver completely disregard the time increments specified where you define the study step), intermediate (where the solver at least makes one computation between two time increments you specify) and strict (where the solver always calculates at the specified times but can take steps inbetween if needed). This is described further in the documentation.

Wiktor


------------------------------
Master student at KTH, Stockholm
Independent consultant in structural analysis
www.wiktorstenstrom.se
Hi Tesfaye, I assume you use a "Time Dependent" study/solver and want to use a variable step size. COMSOL automatically determines (and varies) the needed time step to meet your prescribed tolerances. What you can control is the maximum allowed size of the time step and also whether the steps should be free (where the solver completely disregard the time increments specified where you define the study step), intermediate (where the solver at least makes one computation between two time increments you specify) and strict (where the solver always calculates at the specified times but can take steps inbetween if needed). This is described further in the documentation. Wiktor ------------------------------ Master student at KTH, Stockholm Independent consultant in structural analysis http://www.wiktorstenstrom.se
Tesfaye Tadesse Molla
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Posted: 1 decade ago Mar 8, 2012, 8:17 a.m. EST
Thanks Wiktor,

It seems working now.

Would you have any idea/suggestion on how to mesh very thin layer (27micro meters) interface to a thick layer (400 micrometers) in solid mechanics module as a domain ( i would like to define few domain based deformation parametrs) and have a converging solution ???

I am struggling with such problem and cant get a converging solution or it takes very long time for comsol to run (ofcourse with time dependent solver)

Thanks once again for your suggestions
-Tesfaye
Thanks Wiktor, It seems working now. Would you have any idea/suggestion on how to mesh very thin layer (27micro meters) interface to a thick layer (400 micrometers) in solid mechanics module as a domain ( i would like to define few domain based deformation parametrs) and have a converging solution ??? I am struggling with such problem and cant get a converging solution or it takes very long time for comsol to run (ofcourse with time dependent solver) Thanks once again for your suggestions -Tesfaye
Letian Wang
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Posted: 1 decade ago Nov 6, 2014, 8:21 p.m. EST
Hi Tesfaye!

I am also looking for variable time stepping, so could you tell me how to do that?

Thanks!

Letian


Thanks Wiktor,

It seems working now.

Would you have any idea/suggestion on how to mesh very thin layer (27micro meters) interface to a thick layer (400 micrometers) in solid mechanics module as a domain ( i would like to define few domain based deformation parametrs) and have a converging solution ???

I am struggling with such problem and cant get a converging solution or it takes very long time for comsol to run (ofcourse with time dependent solver)

Thanks once again for your suggestions
-Tesfaye


Hi Tesfaye! I am also looking for variable time stepping, so could you tell me how to do that? Thanks! Letian [QUOTE] Thanks Wiktor, It seems working now. Would you have any idea/suggestion on how to mesh very thin layer (27micro meters) interface to a thick layer (400 micrometers) in solid mechanics module as a domain ( i would like to define few domain based deformation parametrs) and have a converging solution ??? I am struggling with such problem and cant get a converging solution or it takes very long time for comsol to run (ofcourse with time dependent solver) Thanks once again for your suggestions -Tesfaye [/QUOTE]

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