如何获得流域中等值面的最小流向坐标？

[香柏树]

最近在写一个燃烧流场后处理的代码，目的是要提取出以燃烧释热率（Qdot）为1E+10J/m3/s的等值面在流向（y方向）的最小坐标，将其定义为Flame lift-off。目前在OF教程中的aachenBomb案例（图1）基础上进行测试，编译成功的代码如下。但是输出的Flame lift-off值（图2）和paraview中提取的流场数据不一致；比如在0.0004s时Flame lift-off值大概是y=0.075,但是后处理程序输出的是0.1。应该是程序没有遍历整个流域的网格，请问大家知道怎么解决么？个人C++小白，如果需要C++语句的撰写修改，请大家指出方向，我去学习下，非常感谢！

\*---------------------------------------------------------------------------*/

#include "argList.H"
#include "Time.H"
#include "timeSelector.H"
#include "fvCFD.H"
#include "transformGeometricField.H"

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

int main(int argc, char *argv[])
{
    timeSelector::addOptions();
    #include "addRegionOption.H"
 
    #include "setRootCase.H"

    #include "createTime.H"
    instantList timeDirs = timeSelector::select0(runTime, args);
    #include "createMesh.H"

    std::ofstream file("Flame_lifty.plt",ios_base::app); // open a file ++
    forAll(timeDirs, timeI)
    {
    runTime.setTime(timeDirs[timeI], timeI);
    Info<< "Reading field Qdot\n" << endl;

    volScalarField Qdot
    (
        IOobject
        (
            "Qdot",
            runTime.timeName(),
            mesh,
            IOobject::MUST_READ,
            IOobject::NO_WRITE
        ),
        mesh
    );

    
    scalar MinYlocation = 0.1;// maxmimum y position in domain
    //scalar MinQdot = 0.0;
    label index_ = 0;
  

    forAll(Qdot, cellI)
    {
      
     
      if (Qdot[cellI] == scalar(10000000000.0))
      
      {
       // Info << "caculating y position" << endl;
        scalar y = mesh.C()[cellI].component(vector::Y);
        if (y < MinYlocation)
        {
          MinYlocation = y; 
        }
      }
    }
    MinYlocation = mesh.C()[index_].component(vector::Y);
    Info << "   Time= " << runTime.value()<<"," << " Flame lift-off=" << MinYlocation  << endl ;
    file << runTime.value() << " " <<MinYlocation << " " << std::endl;
     
    
    }    
    file.close();  //close the file ++
    return 0;
}


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

[ir77]

@香柏树 楼主您好，请问这个问题您找到解决方法了吗

[香柏树]

@ir77 解决了，需要设置一个误差限，使if语句里二者的值小于误差限就默认二者相等了。

[ir77]

@香柏树 好的，多谢楼主分享