temporalInterpolate.C

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/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Copyright (C) 2011-2026 OpenFOAM Foundation
     \\/     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/>.
 
Description
    Interpolate fields between time-steps e.g. for animation.
 
\*---------------------------------------------------------------------------*/
 
#include "argList.H"
#include "timeSelector.H"
 
#include "fvMesh.H"
#include "Time.H"
#include "volFields.H"
#include "surfaceFields.H"
#include "pointFields.H"
#include "ReadFields.H"
#include "interpolationWeights.H"
#include "uniformInterpolate.H"
 
using namespace Foam;
 
class fieldInterpolator
{
    Time& runTime_;
    const fvMesh& mesh_;
    const IOobjectList& objects_;
    const HashSet<word>& selectedFields_;
    instant ti_;
    instant ti1_;
    const interpolationWeights& interpolator_;
    const wordList& timeNames_;
    int divisions_;
 
public:
 
    fieldInterpolator
    (
        Time& runTime,
        const fvMesh& mesh,
        const IOobjectList& objects,
        const HashSet<word>& selectedFields,
        const instant& ti,
        const instant& ti1,
        const interpolationWeights& interpolator,
        const wordList& timeNames,
        int divisions
    )
    :
        runTime_(runTime),
        mesh_(mesh),
        objects_(objects),
        selectedFields_(selectedFields),
        ti_(ti),
        ti1_(ti1),
        interpolator_(interpolator),
        timeNames_(timeNames),
        divisions_(divisions)
    {}
 
    template<class GeoFieldType>
    void interpolate();
};
 
 
template<class GeoFieldType>
void fieldInterpolator::interpolate()
{
    const word& fieldClassName = GeoFieldType::typeName;
 
    IOobjectList fields = objects_.lookupClass(fieldClassName);
 
    if (fields.size())
    {
        Info<< "    " << fieldClassName << "s:";
 
        forAllConstIter(IOobjectList, fields, fieldIter)
        {
            if
            (
                selectedFields_.empty()
             || selectedFields_.found(fieldIter()->name())
            )
            {
                Info<< " " << fieldIter()->name() << '(';
 
                scalar deltaT = (ti1_.value() - ti_.value())/(divisions_ + 1);
 
                for (int j=0; j<divisions_; j++)
                {
                    instant timej = instant(ti_.value() + (j + 1)*deltaT);
 
                    runTime_.setTime(instant(timej.name()), 0);
 
                    Info<< timej.name();
 
                    if (j < divisions_-1)
                    {
                        Info<< " ";
                    }
 
                    // Calculate times to read and weights
                    labelList indices;
                    scalarField weights;
                    interpolator_.valueWeights
                    (
                        runTime_.value(),
                        indices,
                        weights
                    );
 
                    const wordList selectedTimeNames
                    (
                        UIndirectList<word>(timeNames_, indices)()
                    );
 
                    // Read on the objectRegistry all the required fields
                    ReadFields<GeoFieldType>
                    (
                        fieldIter()->name(),
                        mesh_,
                        selectedTimeNames
                    );
 
                    GeoFieldType fieldj
                    (
                        uniformInterpolate<GeoFieldType>
                        (
                            IOobject
                            (
                                fieldIter()->name(),
                                runTime_.name(),
                                fieldIter()->db(),
                                IOobject::NO_READ,
                                IOobject::NO_WRITE,
                                false
                            ),
                            fieldIter()->name(),
                            selectedTimeNames,
                            weights
                        )
                    );
 
                    fieldj.write();
                }
 
                Info<< ')';
            }
        }
 
        Info<< endl;
    }
}
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
int main(int argc, char *argv[])
{
    timeSelector::addOptions();
    #include "addRegionOption.H"
    argList::addOption
    (
        "fields",
        "list",
        "specify a list of fields to be interpolated. Eg, '(U T p)' - "
        "regular expressions not currently supported"
    );
    argList::addOption
    (
        "divisions",
        "integer",
        "specify number of temporal sub-divisions to create (default = 1)."
    );
    argList::addOption
    (
        "interpolationType",
        "word",
        "specify type of interpolation (linear or spline)"
    );
 
    #include "setRootCaseNoFunctionObjects.H"
    #include "createTimeNoFunctionObjects.H"
 
    HashSet<word> selectedFields;
    if (args.optionFound("fields"))
    {
        args.optionLookup("fields")() >> selectedFields;
    }
    if (selectedFields.size())
    {
        Info<< "Interpolating fields " << selectedFields << nl << endl;
    }
    else
    {
        Info<< "Interpolating all fields" << nl << endl;
    }
 
 
    int divisions = 1;
    if (args.optionFound("divisions"))
    {
        args.optionLookup("divisions")() >> divisions;
    }
    Info<< "Using " << divisions << " per time interval" << nl << endl;
 
 
    const word interpolationType = args.optionLookupOrDefault<word>
    (
        "interpolationType",
        "linear"
    );
    Info<< "Using interpolation " << interpolationType << nl << endl;
 
 
    const instantList timeDirs = timeSelector::select0(runTime, args);
 
    scalarField timeVals(timeDirs.size());
    wordList timeNames(timeDirs.size());
    forAll(timeDirs, i)
    {
        timeVals[i] = timeDirs[i].value();
        timeNames[i] = timeDirs[i].name();
    }
    autoPtr<interpolationWeights> interpolatorPtr
    (
        interpolationWeights::New
        (
            interpolationType,
            timeVals
        )
    );
 
 
    #include "createRegionMeshNoChangers.H"
 
    Info<< "Interpolating fields for times:" << endl;
 
    for (label timei = 0; timei < timeDirs.size() - 1; timei++)
    {
        runTime.setTime(timeDirs[timei], timei);
 
        // Read objects in time directory
        IOobjectList objects(mesh, runTime.name());
 
        fieldInterpolator interpolator
        (
            runTime,
            mesh,
            objects,
            selectedFields,
            timeDirs[timei],
            timeDirs[timei+1],
            interpolatorPtr(),
            timeNames,
            divisions
        );
 
        // Interpolate vol fields
        interpolator.interpolate<volScalarField>();
        interpolator.interpolate<volVectorField>();
        interpolator.interpolate<volSphericalTensorField>();
        interpolator.interpolate<volSymmTensorField>();
        interpolator.interpolate<volTensorField>();
 
        // Interpolate surface fields
        interpolator.interpolate<surfaceScalarField>();
        interpolator.interpolate<surfaceVectorField>();
        interpolator.interpolate<surfaceSphericalTensorField>();
        interpolator.interpolate<surfaceSymmTensorField>();
        interpolator.interpolate<surfaceTensorField>();
    }
 
    Info<< "End\n" << endl;
 
    return 0;
}
 
 
// ************************************************************************* //