FEAP User Forum

FEAP => Programming => Topic started by: william.lnx on August 03, 2017, 12:56:39 PM

Title: Operator splitting time integration
Post by: william.lnx on August 03, 2017, 12:56:39 PM

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. 

Title: Re: Operator splitting time integration
Post by: FEAP_Admin on August 03, 2017, 01:05:11 PM

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.

Title: Re: Operator splitting time integration
Post by: Yaakov on August 07, 2017, 06:03:15 AM

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

Title: Re: Operator splitting time integration
Post by: Prof. R.L. Taylor on August 07, 2017, 06:48:17 AM

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

Title: Re: Operator splitting time integration
Post by: Yaakov on August 07, 2017, 07:11:11 AM

Dear Prof. Taylor,

many many thanks for your answer!

Kind regards,
Yaakov

Title: Re: Operator splitting time integration
Post by: william.lnx on August 08, 2017, 02:40:11 PM

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.

Title: Re: Operator splitting time integration
Post by: Prof. R.L. Taylor on August 08, 2017, 02:51:18 PM

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

Title: Re: Operator splitting time integration
Post by: Prof. S. Govindjee on August 08, 2017, 03:50:53 PM

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.

Title: Re: Operator splitting time integration
Post by: william.lnx on August 16, 2017, 12:07:50 PM

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.

Title: Re: Operator splitting time integration
Post by: Prof. S. Govindjee on August 16, 2017, 01:24:34 PM

include file part0.h, variable npart.

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