# Two fespce combined computation

**URL:** <https://community.freefem.org/t/two-fespce-combined-computation/1413>\
**Category:** General Discussion\
**Created:** [January 6, 2022, 1:03am UTC](https://community.freefem.org/t/two-fespce-combined-computation/1413 "2022-01-06T01:03:01Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![xiaojiemo](https://avatars.discourse-cdn.com/v4/letter/x/a4c791/32.png) [@xiaojiemo](https://community.freefem.org/u/xiaojiemo)\
**Post date:** [January 6, 2022, 1:03am UTC](https://community.freefem.org/t/two-fespce-combined-computation/1413/1 "2022-01-06T01:03:01Z")

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hello,everyone, I am writing a code which includes two regions, porous region and solid particle.and each varaible need to computed separately. who can offer me such examples?  
Thanks

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**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\
**Post date:** [January 6, 2022, 8:37am UTC](https://community.freefem.org/t/two-fespce-combined-computation/1413/2 "2022-01-06T08:37:54Z")

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1. it is not possible to define a **fespace** on 2 meshes.  
but you can add a phantom equation a region with a epsilon to but sur the problem is well defined.
2. Otherwise you can solve the two problems independantly and make a loop to get the good solution.

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<div class="post-metadata">

**Author:** ![xiaojiemo](https://avatars.discourse-cdn.com/v4/letter/x/a4c791/32.png) [@xiaojiemo](https://community.freefem.org/u/xiaojiemo)\
**Post date:** [January 8, 2022, 2:16am UTC](https://community.freefem.org/t/two-fespce-combined-computation/1413/3 "2022-01-08T02:16:35Z")

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if there is an example available?

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<div class="post-metadata">

**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\
**Post date:** [January 10, 2022, 8:29am UTC](https://community.freefem.org/t/two-fespce-combined-computation/1413/4 "2022-01-10T08:29:38Z")

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I have example, but I an no time to explain the example, because the physique if not so simple.

You can try with the coupling of 2 Poissons equations but be careful with Boundary equation.

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**Author:** ![Jamal](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/jamal/32/1527_2.png) [@Jamal](https://community.freefem.org/u/Jamal)\
**Post date:** [August 6, 2022, 5:20pm UTC](https://community.freefem.org/t/two-fespce-combined-computation/1413/5 "2022-08-06T17:20:41Z")

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See :  
[https://doc.freefem.org/models/domain-decomposition.html](https://doc.freefem.org/models/domain-decomposition.html)