How to configure one-way coupling

Using preCICE
2

Hi @Titan,

let’s get the FSI/flap_perp/OpenFOAM-CalculiX example and assume that you want to disable exchanging displacements from CalcluliX to OpenFOAM.

In any case, you can use the config-visualizer to visually validate your precice-config.xml. Here is the original configuration:

config_bi
config_bi1364×336 42.4 KB

  1. In principle, we just need to remove the exchange of Displacements, therefore we remove the following node:
    <exchange data="Displacements0" mesh="Solid" from="Calculix" to="Fluid"/>
    We can then start the two participants as usual. This is not yet ideal, but it runs:
    config_single
    config_single1275×336 42.5 KB

Furthermore, if we would like to cleanup all the involved files:

  1. We should disable the mapping of Displacements0. Currently the Fluid participant (OpenFOAM) maps the Solid mesh to Fluid-Mesh-Nodes, which is not needed anywhere else. So we remove the mapping:
    <mapping:rbf-thin-plate-splines direction="read" from="Solid" to="Fluid-Mesh-Nodes" constraint="consistent"/>
    config_single
    config_single1275×336 42.5 KB
  2. Then, we need to “undefine” the Displacements0 data and the respective read/write operations:
    • Remove the Displacements0 data:
      <data:vector name="Displacements0"/>
    • Remove the Fluid-Mesh-Nodes mesh (only uses Displacement0):
      <mesh name="Fluid-Mesh-Nodes">
    <use-data name="Displacements0"/>
</mesh>
    • Remove Displacements0 from the Solid mesh:
      <use-data name="Displacements0"/>
    • Remove the use of the Fluid-Mesh-Nodes from Fluid and Solid:
      <use-mesh name="Fluid-Mesh-Nodes" provide="yes"/>
    • Remove the read/write operations from the Fluid and Calculix participants:
      <read-data name="Displacements0" mesh="Fluid-Mesh-Nodes"/>
...
<write-data name="Displacements0" mesh="Solid"/>
    Our config now looks much simpler:
    config_single
    config_single1322×251 29.1 KB
  3. Apart from the precice-config.xml, you also need to remove the read/write data and the mesh definitions from your solvers/adapters.
    • In Fluid/system/preciceDict, remove the complete Interface2:
      Interface2
{
  mesh              Fluid-Mesh-Nodes;
  patches           (flap);
  locations         faceNodes;
  
  readData
  (
    Displacements0
  );
  
  writeData
  (
  );
};
    • In config.yml (CalculiX), we need to remove write-data. However, there seems to be a bug in the configuration reading right now. If you cannot wait until we solve it, you could hard-code this in the adapter source code (see issue).
  4. In case you are using implicit coupling (which does not make much sense in a one-way coupling scenario), you also need to remove any convergence measures and replace the data used for the acceleration:
    <absolute-convergence-measure limit="1e-6" data="Displacements0" mesh="Solid"/>

    <acceleration:IQN-ILS>
    <data name="Forces0" mesh="Solid"/>

Here are the respective files:

1 Like