Volume-coupled flow tutorial

volume-coupled-flow/README.md

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+---
+title: Volume-coupled flow
+permalink: tutorials-volume-coupled-flow.html
+keywords: volume coupling, OpenFOAM, source terms
+summary: A dummy source participant is coupled to a fluid in a uni-directional way over a region of the domain. The coupling enforces source terms on that region.
+---
+
+{% note %}
+Get the [case files of this tutorial](https://github.com/precice/tutorials/tree/master/volume-coupled-flow). Read how in the [tutorials introduction](https://www.precice.org/tutorials.html).
+{% endnote %}
+
+## Setup
+
+We introduce flow into a fluid through a square-shaped source located between $$ (3.0, 1.0) $$ and $$ (3.5, 1.5) $$. The velocity at the source is constant in the x component $$ (U.x() = 10.0) $$.
+
+The state of the $$ U.x() $$ of the fluid at $$ t = 0.5s $$ (the source region is highlighted):
+
+![Ux](images/tutorials-volume-coupled-flow-Ux.png)
+
+This case is a convenient starting point for volume coupling where OpenFOAM is a reading participant. The writing Nutils participant (dummy source) can be replaced by a more complex solver according to the user's needs.
+
+## Available solvers
+
+Fluid participant:
+
+* OpenFOAM (buoyantPimpleFoam). For more information, have a look at the [OpenFOAM adapter documentation](https://precice.org/adapter-openfoam-overview.html).
+
+Source participant:
+
+* Nutils. For more information, have a look at the [Nutils adapter documentation](https://www.precice.org/adapter-nutils.html). This Nutils solver requires at least Nutils v7.0.
+
+## Running the simulation
+
+Open two separate terminals and start the participants by calling the respective run scripts `run.sh` located in each of the participants' directory. For example:
+
+```bash
+cd fluid-openfoam
+./run.sh
+```
+
+and
+
+```bash
+cd source-nutils
+./run.sh
+```
+
+## Post-processing
+
+The fluid participants generates a `.foam` file which can be visualized using, e.g., ParaView.
+
+## Notes on the configuration
+
+This case uses OpenFOAM's `fvOptions` to enforce source terms. Additionally, the coupled variable `U` needs to be given an alternative name in order for this to work:
+
+```C++
+FF
+{
+  nameU       U_vol;
+};
+```
+
+Since OpenFOAM already uses `U`, we need to create an additional velocity variable to use specifically for the coupling. That allows us to carry the desired value over to OpenFOAM and apply it at the correct moment in the iteration. A simplified view of the workflow:
+
+![reading-config](images/tutorials-volume-coupled-flow-config.png)

volume-coupled-flow/clean-tutorial.sh

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+../tools/clean-tutorial-base.sh

volume-coupled-flow/fluid-openfoam/0/T

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+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       volScalarField;
+    object      T;
+}
+
+dimensions      [ 0 0 0 1 0 0 0 ];
+
+internalField   uniform 300;
+
+boundaryField
+{
+    inlet
+    {
+        type            fixedValue;
+        value           $internalField;
+    }
+    outlet
+    {
+        type            zeroGradient;
+    }
+    upperWall
+    {
+        type            zeroGradient;
+    }
+    lowerWall
+    {
+        type            zeroGradient;
+    }
+    frontAndBack
+    {
+        type            empty;
+    }
+    defaultFaces
+    {
+        type            empty;
+    }
+}

volume-coupled-flow/fluid-openfoam/0/U

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+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       volVectorField;
+    object      U;
+}
+
+dimensions      [ 0 1 -1 0 0 0 0 ];
+
+internalField   uniform ( 0.1 0 0 );
+
+boundaryField
+{
+    inlet
+    {
+        type            fixedValue;
+        value           $internalField;
+    }
+    outlet
+    {
+        type            zeroGradient;
+    }
+    upperWall
+    {
+        type            noSlip;
+    }
+    lowerWall
+    {
+        type            noSlip;
+    }
+    frontAndBack
+    {
+        type            empty;
+    }
+    defaultFaces
+    {
+        type            empty;
+    }
+}

volume-coupled-flow/fluid-openfoam/0/U_vol

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+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       volVectorField;
+    object      U_vol;
+}
+
+dimensions      [ 0 1 -1 0 0 0 0 ];
+
+internalField   uniform ( 0.1 0 0 );
+
+boundaryField
+{
+    inlet
+    {
+        type            fixedValue;
+        value           $internalField;
+    }
+    outlet
+    {
+        type            zeroGradient;
+    }
+    upperWall
+    {
+        type            noSlip;
+    }
+    lowerWall
+    {
+        type            noSlip;
+    }
+    frontAndBack
+    {
+        type            empty;
+    }
+    defaultFaces
+    {
+        type            empty;
+    }
+}

volume-coupled-flow/fluid-openfoam/0/alphat

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+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       volScalarField;
+    object      alphat;
+}
+
+dimensions      [ 1 -1 -1 0 0 0 0 ];
+
+internalField   uniform 0;
+
+boundaryField
+{
+    inlet
+    {
+        type            compressible::alphatWallFunction;
+        value           uniform 0;
+    }
+    outlet
+    {
+        type            compressible::alphatWallFunction;
+        value           uniform 0;
+    }
+    upperWall
+    {
+        type            compressible::alphatWallFunction;
+        value           uniform 0;
+    }
+    lowerWall
+    {
+        type            compressible::alphatWallFunction;
+        value           uniform 0;
+    }
+    frontAndBack
+    {
+        type            empty;
+    }
+    defaultFaces
+    {
+        type            empty;
+    }
+}

volume-coupled-flow/fluid-openfoam/0/epsilon

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+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       volScalarField;
+    object      epsilon;
+}
+
+dimensions      [ 0 2 -3 0 0 0 0 ];
+
+internalField   uniform 0.01;
+
+boundaryField
+{
+    inlet
+    {
+        type            epsilonWallFunction;
+        value           uniform 0.01;
+    }
+    outlet
+    {
+        type            epsilonWallFunction;
+        value           uniform 0.01;
+    }
+    upperWall
+    {
+        type            epsilonWallFunction;
+        value           uniform 0.01;
+    }
+    lowerWall
+    {
+        type            epsilonWallFunction;
+        value           uniform 0.01;
+    }
+    frontAndBack
+    {
+        type            empty;
+    }
+    defaultFaces
+    {
+        type            empty;
+    }
+}

volume-coupled-flow/fluid-openfoam/0/k

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+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       volScalarField;
+    object      k;
+}
+
+dimensions      [ 0 2 -2 0 0 0 0 ];
+
+internalField   uniform 0.1;
+
+boundaryField
+{
+    inlet
+    {
+        type            kqRWallFunction;
+        value           uniform 0.1;
+    }
+    outlet
+    {
+        type            kqRWallFunction;
+        value           uniform 0.1;
+    }
+    upperWall
+    {
+        type            kqRWallFunction;
+        value           uniform 0.1;
+    }
+    lowerWall
+    {
+        type            kqRWallFunction;
+        value           uniform 0.1;
+    }
+    frontAndBack
+    {
+        type            empty;
+    }
+    defaultFaces
+    {
+        type            empty;
+    }
+}

volume-coupled-flow/fluid-openfoam/0/nut

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+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       volScalarField;
+    object      nut;
+}
+
+dimensions      [ 0 2 -1 0 0 0 0 ];
+
+internalField   uniform 0;
+
+boundaryField
+{
+    inlet
+    {
+        type            nutkWallFunction;
+        value           uniform 0;
+    }
+    outlet
+    {
+        type            nutkWallFunction;
+        value           uniform 0;
+    }
+    upperWall
+    {
+        type            nutkWallFunction;
+        value           uniform 0;
+    }
+    lowerWall
+    {
+        type            nutkWallFunction;
+        value           uniform 0;
+    }
+    frontAndBack
+    {
+        type            empty;
+    }
+    defaultFaces
+    {
+        type            empty;
+    }
+}