# Infinite Flow Plane

**URL:** <https://discourse.opengeosys.org/t/infinite-flow-plane/1733>\
**Category:** Help & Support\
**Created:** [November 12, 2025, 9:25am UTC](https://discourse.opengeosys.org/t/infinite-flow-plane/1733 "2025-11-12T09:25:57Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![ShF](https://discourse.opengeosys.org/letter_avatar_proxy/v4/letter/s/f08c70/32.png) [@ShF](https://discourse.opengeosys.org/u/ShF)\
**Post date:** [November 12, 2025, 9:25am UTC](https://discourse.opengeosys.org/t/infinite-flow-plane/1733/1 "2025-11-12T09:25:57Z")

</div>

Hello,  
Is it possible to set outflow boundaries to no condition? I have a 2D fracture plane, modeling the flow diffusion from injecting flow rate. But, as far as I know OGS sets the no flow condition on the outer boundary lines. I want a free flow condition without any fixed pressure set. How should I set that up?  
Thanks

---

<div class="post-metadata">

**Author:** ![joergbuchwald](https://discourse.opengeosys.org/user_avatar/discourse.opengeosys.org/joergbuchwald/32/449_2.png) [@joergbuchwald](https://discourse.opengeosys.org/u/joergbuchwald)\
**Post date:** [November 12, 2025, 10:25am UTC](https://discourse.opengeosys.org/t/infinite-flow-plane/1733/2 "2025-11-12T10:25:59Z")

</div>

Hi!  
without any BCs the mathematical problem would not be well-defined.  
What you are probably looking for are infinite mapped elements. The issue with these are that they require special shape functions that map the infinite domain onto a finite reference element, which are not yet implemented in OGS.  
The way to go in OGS is to set up a sufficiently large model in which finite size effects are negligible.  
I.e. setting Dirichlet or in you case probably better Neumann, far-field values. (If you have a diffusion problem, you would guess that at certain domain size the gradient should approach zero). To find out the required domain size you might need to perform a convergence study.