OpenFOAMThe level class

OpenFOAMV9中的isoSurfaceClass can be used to提取等值面.
An instance of this class is the way to：

sampledSurfaces::isoSurface isosurf = sampledSurfaces::isoSurface(
            "isoSurface",
            mesh,
            isoSurfaceDict);

"isoSurface"是一个自定义的名字（Generally take object name）,meshIs a research problem by grid,isoSurfaceDict是一个数据字典,The data dictionary content is as follows

/*--------------------------------*- C++ -*----------------------------------*\ ========= | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox \\ / O peration | Website: https://openfoam.org \\ / A nd | Version: 9 \\/ M anipulation | ------------------------------------------------------------------------------- Description Writes out iso-surface files with interpolated field data in VTK format. \*---------------------------------------------------------------------------*/
FoamFile
{
    
    format      ascii;
    class       dictionary;
    location    "system";
    object      isoSurfaceDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

type        isoSurface;
isoField    p;		//Need to extract the contour field,Here is the pressure field
isoValue    10;	//Contour of numerical,Here are three10Pa
filter      full;
interpolate yes;

// ************************************************************************* //

有了isosurf这个对象之后,Can use the following line of code completion isosurface extraction work

isosurf.sample(p);

After completing level extract,Can get the level surface unit vector and equivalent to the vertex coordinates

//The level surface unit vector
faceList faces = isosurf.faces();
//Equivalent to the vertex coordinates
pointField points = isosurf.points();

pointsDescribes the contour surface is made up of what point,Provides information on the coordinates of these points.facesDescribe the relationship between the point of connection.如果要访问第faceIOn the surface of the cell area,可以使用以下代码:

mag(faces[faceI].area(points))

为了方便可视化,Can also get the level of output forVTK文件

vtkSurfaceWriter vtkWriter = vtkSurfaceWriter(IOstream::streamFormat::ASCII);
vtkWriter.write("postProcess",
                "someContours",
                points,
                faces);

代码

教程案例

In the tutorial examplepitzDaily为例子,Copy it to your folder.使用simpleFoamSolver complete solution,结果如下：

Modify the solver

在simpleFoamSolver on the basis of the source code to add the content of equivalent plane,The improved solvermain函数如下

/*---------------------------------------------------------------------------*\ ========= | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox \\ / O peration | Website: https://openfoam.org \\ / A nd | Copyright (C) 2011-2021 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/>. Application isoSimpleFoam Description Steady-state solver for incompressible, turbulent flow, using the SIMPLE algorithm. \*---------------------------------------------------------------------------*/

#include "fvCFD.H"
#include "singlePhaseTransportModel.H"
#include "kinematicMomentumTransportModel.H"
#include "simpleControl.H"
#include "pressureReference.H"
#include "fvModels.H"
#include "fvConstraints.H"
//The header file of equivalent plane
#include "sampledIsoSurface.H"
#include "vtkSurfaceWriter.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

int main(int argc, char *argv[])
{
    
#include "postProcess.H"

#include "setRootCaseLists.H"
#include "createTime.H"
#include "createMesh.H"
#include "createControl.H"
#include "createFields.H"
#include "initContinuityErrs.H"

    //Read the isoline dictionary
    dictionary isoSurfaceDict = IOdictionary(IOobject(
        "isoSurfaceDict",
        mesh.time().system(),
        mesh,
        IOobject::MUST_READ,
        IOobject::NO_WRITE));

    turbulence->validate();

    // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

    Info << "\nStarting time loop\n"
         << endl;

    while (simple.loop(runTime))
    {
    
        Info << "Time = " << runTime.timeName() << nl << endl;

        fvModels.correct();

        // --- Pressure-velocity SIMPLE corrector
        {
    
#include "UEqn.H"
#include "pEqn.H"
        }

        laminarTransport.correct();
        turbulence->correct();

        //Modify the contour in the dictionaryisoValue数值
        isoSurfaceDict.set("isoValue", 7);
        //实例化isoSurface对象
        sampledSurfaces::isoSurface isosurf = sampledSurfaces::isoSurface(
            "isoSurface",
            mesh,
            isoSurfaceDict);
        //提取等值面
        isosurf.sample(p);
        //The level surface unit vector
        faceList faces = isosurf.faces();
        //Equivalent to the vertex coordinates
        pointField points = isosurf.points();
        //Calculated the level area
        scalar area = 0;
        forAll(faces, faceI)
        {
    
            area += mag(faces[faceI].area(points));
        }
        Info << "面积:" << area << endl;
        //Will output level asVTK文件
        vtkSurfaceWriter vtkWriter = vtkSurfaceWriter(IOstream::streamFormat::ASCII);
        vtkWriter.write("postProcess",
                        "someContours",
                        points,
                        faces);

        runTime.write();

        Info << "ExecutionTime = " << runTime.elapsedCpuTime() << " s"
             << " ClockTime = " << runTime.elapsedClockTime() << " s"
             << nl << endl;
    }

    Info << "End\n"
         << endl;

    return 0;
}

// ************************************************************************* //

The process of compilation to seeOpenFOAM用户手册,Here introduces basic steps only.
新建Make文件夹,在Make文件夹中新建files文件,Write to compile information

isoSimpleFoam.C

EXE = $(FOAM_USER_APPBIN)/isoSimpleFoam

在Make文件夹中新建options文件,Write to rely on information

EXE_INC = \
    -I$(LIB_SRC)/MomentumTransportModels/momentumTransportModels/lnInclude \
    -I$(LIB_SRC)/MomentumTransportModels/incompressible/lnInclude \
    -I$(LIB_SRC)/transportModels/lnInclude \
    -I$(LIB_SRC)/finiteVolume/lnInclude \
    -I$(LIB_SRC)/meshTools/lnInclude \
    -I$(LIB_SRC)/sampling/lnInclude \
    -I$(LIB_SRC)/surfMesh/lnInclude

EXE_LIBS = \
    -lmomentumTransportModels \
    -lincompressibleMomentumTransportModels \
    -ltransportModels \
    -lfiniteVolume \
    -lmeshTools \
    -lfvModels \
    -lfvConstraints \
    -lsampling\
    -lsurfMesh

使用wmake命令完成编译,得到isoSimpleFoam求解器.The solver will calculatepitzDailyCase pressure for7PaThe level of area,并输出为VTK文件.

7Pa等值面

计算完成后,使用paraview读取postProcess文件夹下的someContours.vtk文件,可得到下图

This is the extraction of contour surface,其面积为9.043e-05