# Minimizing Interpolation Mapping Errors Across Mismatched Fluid-Structure Interface Meshes

**URL:** <https://precice.discourse.group/t/minimizing-interpolation-mapping-errors-across-mismatched-fluid-structure-interface-meshes/3013>\
**Category:** Installing preCICE\
**Created:** [November 6, 2026, 2:54am UTC](https://precice.discourse.group/t/minimizing-interpolation-mapping-errors-across-mismatched-fluid-structure-interface-meshes/3013 "2026-11-06T02:54:37Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![cadguide](https://avatars.discourse-cdn.com/v4/letter/c/a9a28c/32.png) [@cadguide](https://precice.discourse.group/u/cadguide)\
**Post date:** [November 6, 2026, 2:54am UTC](https://precice.discourse.group/t/minimizing-interpolation-mapping-errors-across-mismatched-fluid-structure-interface-meshes/3013/1 "2026-11-06T02:54:37Z")

</div>

In multi-physics fluid-structure interaction (FSI) simulations coupling OpenFOAM with structural FEM solvers via preCICE, spatial interpolation at the wet interface often suffers from numerical diffusion when mesh resolutions differ by more than an order of magnitude.

When mapping forces from a fine boundary layer mesh (with dense prism cells) to a coarser structural surface mesh, radial basis function (RBF) data mapping with thin-plate splines provides superior conservation compared to nearest-neighbor projection:

```xml
<mapping:rbf-thin-plate-splines
  direction="write"
  from="Fluid-Mesh"
  to="Solid-Mesh"
  constraint="conservative" />

```

### Key Considerations for Curvature Preservation

- On curved aerodynamic profiles or turbine blades, ensuring that both participating CAD models share the exact same chordal tolerance prevents artificial gap formation during displacement write-back.
- When extracting structural boundary surfaces from neutral CAD geometry, verifying geometric tolerances beforehand avoids node projection failures. For checking engineering dimensional fits and interface tolerances, we maintain a free reference tool at [CADGuide.tools Engineering Tolerance & Limit Calculator](https://cadguide.tools/toolbox/step-file-header-parser).

What shape parameter tuning strategies are people finding most stable for high-deformation FSI with OpenFOAM and preCICE?