Operator splitting time integration

[william.lnx]

Hello everyone,

I am trying to do operator splitting time integration analysis using FEAP. Is there any way of doing this easily in FEAP? I am particularly interested in nonlinear heat equations.

Regards. 

[FEAP_Admin]

You can do this with the PARTition command.  This allows you to set which dofs are active in each part of the split.  Then in the solution phase you can set the active partition and solve, then change to the next partition and solve, etc.

[Yaakov]

Dear FEAP Administrator,

I would like to continue this topic, for nonlinear thermo-mechnical problem (fully), can I use  PARTition command as the tangent matrix is unsymmetry?


Warm regards,
Yaakov

[Prof. R.L. Taylor]

yes,  you only need to use UTAN instead of TANG if the partitioned matrix is unsymmetric.  If any partition has symmetric then still use TANG in these

[Yaakov]

Dear Prof. Taylor,

many many thanks for your answer!

Kind regards,
Yaakov

[william.lnx]

Thanks for your answer,

On the other hand, Is there any way in which the information is shared in each partition?

I want to compute some variables in the first partition and then use this information for the 2nd and 3th partition, but I do not see the way of doing this.

Thank you in advance.

[Prof. R.L. Taylor]

Current values for all dof's should be in the element 'ul' array for every partition. 

[Prof. S. Govindjee]

If what you want to access is not part of the local arrays already, then I think you can try using the history option defined by setting nh3 under isw.eq.1 in your element.

[william.lnx]

Thank you,

Your answers have been very helpful.

I have implemented an splitting using the PARTition command and the parameters ctan() in order to activate zero and first order integrations. Now, let me ask something else ¿there is any way to know which partition is activated inside an user element?.

Regards.

[Prof. S. Govindjee]

include file part0.h, variable npart.

look in program/pmacr6.f to see how the PARTition command works; see also program/partpt.f