ENH: Added new utility to create a box of isotropic turbulence

applications/utilities/preProcessing/createBoxTurb/Make/files

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+createBoxTurb.C
+
+EXE = $(FOAM_APPBIN)/createBoxTurb

applications/utilities/preProcessing/createBoxTurb/Make/options

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+EXE_INC = \
+    -I$(LIB_SRC)/finiteVolume/lnInclude \
+    -I$(LIB_SRC)/meshTools/lnInclude \
+    -I$(LIB_SRC)/mesh/blockMesh/lnInclude \
+    -I$(LIB_SRC)/fileFormats/lnInclude
+
+
+EXE_LIBS = \
+    -lfiniteVolume \
+    -lmeshTools \
+    -lblockMesh \
+    -lfileFormats

applications/utilities/preProcessing/createBoxTurb/createBlockMesh.H

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+const cellModel& hex = cellModel::ref(cellModel::HEX);
+
+cellShapeList cellShapes;
+faceListList boundary;
+pointField points;
+{
+    Info<< "Creating block" << endl;
+
+    block b
+    (
+        cellShape(hex, identity(8), false),
+        pointField
+        (
+            {
+                point(0, 0, 0),
+                point(L.x(), 0, 0),
+                point(L.x(), L.y(), 0),
+                point(0, L.y(), 0),
+                point(0, 0, L.z()),
+                point(L.x(), 0, L.z()),
+                point(L.x(), L.y(), L.z()),
+                point(0, L.y(), L.z())
+            }
+        ),
+        blockEdgeList(),
+        blockFaceList(),
+        N,
+        List<gradingDescriptors>(12)
+    );
+
+    Info<< "Creating cells" << endl;
+
+    List<FixedList<label, 8>> bCells(b.cells());
+    cellShapes.setSize(bCells.size());
+    forAll(cellShapes, celli)
+    {
+        cellShapes[celli] =
+            cellShape(hex, labelList(bCells[celli]), false);
+    }
+
+    Info<< "Creating boundary faces" << endl;
+
+    boundary.setSize(b.boundaryPatches().size());
+    forAll(boundary, patchi)
+    {
+        faceList faces(b.boundaryPatches()[patchi].size());
+        forAll(faces, facei)
+        {
+            faces[facei] = face(b.boundaryPatches()[patchi][facei]);
+        }
+        boundary[patchi].transfer(faces);
+    }
+
+    points.transfer(const_cast<pointField&>(b.points()));
+}
+
+Info<< "Creating patch dictionaries" << endl;
+wordList patchNames(boundary.size());
+forAll(patchNames, patchi)
+{
+    patchNames[patchi] = "patch" + Foam::name(patchi);
+}
+
+PtrList<dictionary> boundaryDicts(boundary.size());
+forAll(boundaryDicts, patchi)
+{
+    boundaryDicts.set(patchi, new dictionary());
+    dictionary& patchDict = boundaryDicts[patchi];
+    word nbrPatchName;
+    if (patchi % 2 == 0)
+    {
+        nbrPatchName = "patch" + Foam::name(patchi + 1);
+    }
+    else
+    {
+        nbrPatchName = "patch" + Foam::name(patchi - 1); 
+    }
+
+    patchDict.add("type", cyclicPolyPatch::typeName);
+    patchDict.add("neighbourPatch", nbrPatchName);
+}
+
+Info<< "Creating polyMesh" << endl;
+polyMesh mesh
+(
+    IOobject
+    (
+        polyMesh::defaultRegion,
+        runTime.constant(),
+        runTime,
+        IOobject::NO_READ
+    ),
+    std::move(points),
+    cellShapes,
+    boundary,
+    patchNames,
+    boundaryDicts,
+    "defaultFaces",
+    cyclicPolyPatch::typeName,
+    false
+);
+
+Info<< "Writing polyMesh" << endl;
+mesh.write();

applications/utilities/preProcessing/createBoxTurb/createBoxTurb.C

@@ -0,0 +1,184 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2018 OpenCFD Ltd.
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Application
+    createBoxTurb
+
+Description
+    Creates a box of isotropic turbulence based on a user-specified
+    energy spectrum.
+
+    Based on the reference
+    \verbatim
+    Saad, T., Cline, D., Stoll, R., Sutherland, J.C.
+    "Scalable Tools for Generating Synthetic Isotropic Turbulence with
+    Arbitrary Spectra"
+    AIAA Journal, Vol. 55, No. 1 (2017), pp. 327-331.
+    \endverbatim
+
+    The \c -createBlockMesh option creates a block mesh and exits, which
+    can then be decomposed and the utility run in parallel.
+
+\*---------------------------------------------------------------------------*/
+
+#include "fvCFD.H"
+#include "block.H"
+#include "mathematicalConstants.H"
+
+using namespace Foam::constant;
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+Foam::vector randomUnitVector(Random& rndGen)
+{
+    // Sample point on a sphere
+    scalar t = rndGen.globalPosition<scalar>(-1, 1);
+    scalar phim = rndGen.globalSample01<scalar>()*mathematical::twoPi;
+    scalar thetam = Foam::acos(t);
+
+    return vector
+    (
+        Foam::sin(thetam*Foam::cos(phim)),
+        Foam::sin(thetam*Foam::sin(phim)),
+        Foam::cos(thetam)
+    );
+}
+
+
+int main(int argc, char *argv[])
+{
+    argList::addBoolOption
+    (
+        "createBlockMesh",
+        "create the block mesh and exit"
+    );
+
+    #include "setRootCase.H"
+
+    #include "createTime.H"
+    #include "createFields.H"
+
+    if (args.found("createBlockMesh"))
+    {
+        // Create a box block mesh with cyclic patches
+        #include "createBlockMesh.H"
+        return 0;
+    }
+
+    #include "createMesh.H"
+
+    // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+    // Minimum wave number
+    scalar kappa0 = mathematical::twoPi/cmptMin(L);
+
+    // Maximum wave number
+    scalar kappaMax = mathematical::pi/cmptMin(delta);
+
+    Info<< "Wave number min/max = " << kappa0 << ", " << kappaMax << endl;
+
+    Info<< "Generating velocity field" << endl;
+
+    volVectorField U
+    (
+        IOobject
+        (
+            "U",
+            runTime.timeName(),
+            mesh,
+            IOobject::NO_READ,
+            IOobject::NO_WRITE
+        ),
+        mesh,
+        dimensionedVector(dimVelocity, Zero)
+    );
+
+    vectorField& Uc = U.primitiveFieldRef();
+    const scalar deltaKappa = (kappaMax - kappa0)/scalar(nModes - 1);
+    const vectorField& C(mesh.C());
+    for (label modei = 1; modei <= nModes; ++modei)
+    {
+        // Equidistant wave mode
+        scalar kappaM = kappa0 + deltaKappa*(modei-1);
+
+        Info<< "Processing mode:" << modei << " kappaM:" << kappaM << endl;
+
+        // Energy
+        scalar E = Ek->value(kappaM);
+
+        // Wave amplitude
+        scalar qm = Foam::sqrt(E*deltaKappa);
+
+        // Wave number unit vector
+        const vector kappaHatm(randomUnitVector(rndGen));
+
+        vector kappaTildem(0.5*kappaM*cmptMultiply(kappaHatm, delta));
+        for (direction i = 0; i < 3; ++i)
+        {
+            kappaTildem[i] = 2/delta[i]*Foam::sin(kappaTildem[i]);
+        }
+
+        // Intermediate unit vector zeta
+        const vector zetaHatm(randomUnitVector(rndGen));
+
+        // Unit vector sigma
+        vector sigmaHatm(zetaHatm^kappaTildem);
+        sigmaHatm /= mag(kappaTildem);
+
+        // Phase angle
+        scalar psim = 0.5*rndGen.position(-mathematical::pi, mathematical::pi);
+
+        // Add the velocity contribution per mode
+        Uc += 2*qm*cos(kappaM*(kappaHatm & C) + psim)*sigmaHatm;
+    }
+
+    U.write();
+
+    {
+        Info<< "Generating kinetic energy field" << endl;
+        volScalarField k("k", 0.5*magSqr(U));
+        k.write();
+        Info<< "min/max/average k = "
+            << gMin(k) << ", " << gMax(k) << ", " << gAverage(k)
+            << endl;
+    }
+
+    {
+        Info<< "Generating div(U) field" << endl;
+        volScalarField divU(fvc::div(U));
+        divU.write();
+        Info<< "min/max/average div(U) = "
+            << gMin(divU) << ", " << gMax(divU) << ", " << gAverage(divU)
+            << endl;
+    }
+
+    Info<< nl;
+    runTime.printExecutionTime(Info);
+
+    Info<< "End\n" << endl;
+
+    return 0;
+}
+
+
+// ************************************************************************* //

applications/utilities/preProcessing/createBoxTurb/createFields.H

@@ -0,0 +1,33 @@
+IOdictionary dict
+(
+    IOobject
+    (
+        "createBoxTurbDict",
+        runTime.constant(),
+        runTime,
+        IOobject::MUST_READ
+    )
+);
+
+// Extents in x, y, z directions
+const vector L(dict.get<vector>("L"));
+
+// Number of cells in x, y, z directions
+const Vector<label> N(dict.get<Vector<label>>("N"));
+
+// Wave number vs energy profile
+autoPtr<Function1<scalar>> Ek(Function1<scalar>::New("E", dict));
+
+// Number of modes
+const label nModes = dict.get<label>("nModes");
+
+// Mesh spacing in x, y and z directions
+const vector delta
+(
+    L.x()/scalar(N.x()),
+    L.y()/scalar(N.y()),
+    L.z()/scalar(N.z())
+);
+
+Random rndGen(1234);
+