# How to implement a 3D-to-1D mapping？

**URL:** <https://precice.discourse.group/t/how-to-implement-a-3d-to-1d-mapping/2607>\
**Category:** Using preCICE\
**Tags:** openfoam, data-mapping, calculix, fsi, geometric-multiscale\
**Created:** [September 1, 2025, 3:05am UTC](https://precice.discourse.group/t/how-to-implement-a-3d-to-1d-mapping/2607 "2025-09-01T03:05:06Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![HHao-gihub](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/hhao-gihub/32/2930_2.png) [@HHao-gihub](https://precice.discourse.group/u/HHao-gihub)\
**Post date:** [September 1, 2025, 3:05am UTC](https://precice.discourse.group/t/how-to-implement-a-3d-to-1d-mapping/2607/1 "2025-09-01T03:05:06Z")

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I plan to perform fluid-structure interaction analysis on a fishing net using OpenFOAM and Calculix. For the net, I will use 1D beam elements B32. Since the fluid domain in OpenFOAM is 3D, what mapping method should I employ?

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**Author:** ![IshaanDesai](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/ishaandesai/32/1048_2.png) [@IshaanDesai](https://precice.discourse.group/u/IshaanDesai)\
**Post date:** [October 1, 2025, 9:08am UTC](https://precice.discourse.group/t/how-to-implement-a-3d-to-1d-mapping/2607/2 "2025-10-01T09:08:47Z")

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Please take a look at [geometric multiscale mapping](https://precice.org/configuration-mapping.html#geometric-multiscale-mapping).

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**Author:** ![Makis](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/makis/32/25_2.png) [@Makis](https://precice.discourse.group/u/Makis)\
**Post date:** [October 8, 2025, 8:11am UTC](https://precice.discourse.group/t/how-to-implement-a-3d-to-1d-mapping/2607/3 "2025-10-08T08:11:27Z")

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That would indeed be an interesting case for the geometric multiscale mapping (you would need a radial mapping to map the 1D ropes on the 3D fluid and the reverse), but I would not expect this to work out of the box without some tinkering.

I assume you want to do FSI, where you have the fishing net immersed into water. You still need to define some surface on which to compute forces. I would rather try to implement this conversion (3D to 1D and defining a coupling mesh) in the 1D code for now. Note also that preCICE does not yet support 1D meshes (but working on it).

See also:

> [@FSI coupling OpenFOAM (solving 3D fluid) and Calculix (solving 1D structure)](https://precice.discourse.group/t/fsi-coupling-openfoam-solving-3d-fluid-and-calculix-solving-1d-structure/2196):
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> Hello everyone! 1. Model description I am trying to simulate a classic fluid-structure interaction (FSI) problem, specifically the deformation of a flexible cylinder under incoming flow. I’m using OpenFOAM to solve the fluid domain and CalculiX to solve the structural domain. Given that my model has a high length-to-diameter ratio and the Reynolds number is quite high (requiring LES simulation), I’m attempting to reduce the computational load by using a 3D fluid mesh coupled with a 1D structur…

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**Author:** ![HHao-gihub](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/hhao-gihub/32/2930_2.png) [@HHao-gihub](https://precice.discourse.group/u/HHao-gihub)\
**Post date:** [October 9, 2025, 5:57am UTC](https://precice.discourse.group/t/how-to-implement-a-3d-to-1d-mapping/2607/4 "2025-10-09T05:57:17Z")

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[calculix.log.txt](https://precice.discourse.group/uploads/short-url/ae9Jt127zD9GZhFpZoF9Chnj2DM.txt) (10.3 KB)

[precice-config.xml.txt](https://precice.discourse.group/uploads/short-url/w9jX6AcPROr910472q9DEkP4tnZ.txt) (3.0 KB)

[openfoam.log.txt](https://precice.discourse.group/uploads/short-url/yBdnPZberVP4yWYn3QUL3PuZBPu.txt) (2.3 KB)

I referred to the post you mentioned and tried using radial mapping, but encountered issues similar to those described in that post. My fishing net was constructed using B32 beam elements.