# Fluid solver mesh - How to link a solid mesh with a fluid mesh **URL:** \ **Category:** Is preCICE for me?\ **Tags:** openfoam, adapters, python\ **Created:** [May 24, 2021, 6:09pm UTC](https://precice.discourse.group/t/fluid-solver-mesh-how-to-link-a-solid-mesh-with-a-fluid-mesh/604 "2021-05-24T18:09:45Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![JulianSchl](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/julianschl/32/692_2.png) [@JulianSchl](https://precice.discourse.group/u/JulianSchl)\ **Post date:** [May 24, 2021, 6:09pm UTC](https://precice.discourse.group/t/fluid-solver-mesh-how-to-link-a-solid-mesh-with-a-fluid-mesh/604/1 "2021-05-24T18:09:45Z")
Hi, having implemented a structure solver with the python interface of preCICE, I am now planning to couple a OpenFOAM fluid solver with preCICE. In the documentation the implementation doesn’t seem to be very difficult but looking at the mesh, I am wondering how I set up the correct mesh for the fluid solver. **Current status:** I have set up a mesh for the moving points of my rigid body in the solid solver. **Plan:** - Implementation of the fluid solver → First coupling to a [solverdummy](https://github.com/precice/python-bindings/tree/develop/solverdummy) - If necessary: Creation of a new mesh for the fluid solver. For the fluid solver I will need the points of the rigid body transfered to cells and in addition I will need the cells of the farfield around the moving body. **Question:** Is there a way in preCICE to link specific cells (of the fluid mesh) to points (of the solid mesh) or do I have to add the farfield cells around my rigid body (transformed to points) to the solid mesh? For the solid mesh, I have simplified the case to just a few points, but looking at the fluid solver, it seems to get a huge work, or am I missing an easy way to link solid an fluid mesh? My first step would be to couple my current fluid simulation (mesh with many cells) with a [solverdummy](https://github.com/precice/python-bindings/tree/develop/solverdummy), but I don’t know how to create the mesh there. ---
**Author:** ![DavidSCN](https://avatars.discourse-cdn.com/v4/letter/d/c37758/32.png) [@DavidSCN](https://precice.discourse.group/u/DavidSCN)\ **Post date:** [May 25, 2021, 7:48am UTC](https://precice.discourse.group/t/fluid-solver-mesh-how-to-link-a-solid-mesh-with-a-fluid-mesh/604/2 "2021-05-25T07:48:10Z")
Hi @JulianSchl, I’m not sure if I unserstand your problem correct. > [@JulianSchl](#): > > having implemented a structure solver with the python interface of preCICE, > I am now planning to couple a OpenFOAM fluid solver with preCICE. > In the documentation the implementation doesn’t seem to be very difficult but looking at the mesh, > I am wondering how I set up the correct mesh for the fluid solver. I guess you have already seen our OpenFOAM tutorials? > [@JulianSchl](#): > > Implementation of the fluid solver → First coupling to a [solverdummy](https://github.com/precice/python-bindings/tree/develop/solverdummy) Is there any special reason to implement a fluid solver yourself? Why not using an OpenFOAM solver? > [@JulianSchl](#): > > For the fluid solver I will need the points of the rigid body transfered to cells and in addition I will need the cells of the farfield around the moving body. Why do you need the far-field cells? Do you really talk about cells or cell-faces? For me, it sound a bit like volume coupling instead of surface coupling? May I ask you to explain this a bit more in detail? > [@JulianSchl](#): > > Is there a way in preCICE to link specific cells (of the fluid mesh) to points (of the solid mesh) or do I have to add the farfield cells around my rigid body (transformed to points) to the solid mesh? > For the solid mesh, I have simplified the case to just a few points, but looking at the fluid solver, it seems to get a huge work, or am I missing an easy way to link solid an fluid mesh? The ‘link’ is essentially the mapping in preCICE. If you really want to connect cells and points in a user-defined arbitrary fashion- that’s currently not possible. However, if you want to link cells and points in a clear and debug-able way you could select a nearest-neighbor mapping in your preCICE configuration. As the name suggests, the nearest-neighbor mapping links the nearest neighbors on your coupling interface. Still, I’m not sure if this is really what you were asking for. Usually, you don’t need to exchange far-field cells for standard FSI applications. ---
**Author:** ![JulianSchl](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/julianschl/32/692_2.png) [@JulianSchl](https://precice.discourse.group/u/JulianSchl)\ **Post date:** [June 7, 2021, 8:49pm UTC](https://precice.discourse.group/t/fluid-solver-mesh-how-to-link-a-solid-mesh-with-a-fluid-mesh/604/3 "2021-06-07T20:49:32Z")
> [@DavidSCN](#): > > Is there any special reason to implement a fluid solver yourself? Why not using an OpenFOAM solver? I am sorry, I expressed myself wrong, I do not want to implement a solver, but use the existing _displacementLaplacian_ solver. > [@DavidSCN](#): > > Why do you need the far-field cells? Do you really talk about cells or cell-faces? For me, it sound a bit like volume coupling instead of surface coupling? May I ask you to explain this a bit more in detail? The farfield case is already created. It seems, that I didn’t express myself properly. Working some time with the OpenFOAM-Adapter, I have achieved a successful coupling and now understand, that I don’t have to map from cell to cell, but from mesh to mesh, which gets interpolated by preCICE. ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/precice/original/1X/67d2a5fa6f80e597e2267ff17fa8c1673cd11caa.svg) [@system](https://precice.discourse.group/u/system)\ **Post date:** [June 10, 2021, 8:50pm UTC](https://precice.discourse.group/t/fluid-solver-mesh-how-to-link-a-solid-mesh-with-a-fluid-mesh/604/4 "2021-06-10T20:50:06Z")
Closed on June 10, 2021, 8:50pm UTC This topic was automatically closed 3 days after the last reply. New replies are no longer allowed.