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How to control the heat source according to the temperature of a point?

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Old   December 13, 2022, 09:49
Default How to control the heat source according to the temperature of a point?
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chenfuqiang
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Dear community,
I want to get the temperature ''Tpoint'' at a point in the geometry. When Tpoint ≥150℃, set the heat source to 0, and when Tpoint < 150℃, set the heat source to a value, like 100.Can I get the ''Tpoint'' using the probe? Can I add an if statement about Tpoint before the energy equation of the solver?
Could you give me some tips to achieve this?
Thank you in advance.
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Old   December 19, 2022, 10:18
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fvOptions or fvModels should do the trick here.
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Old   January 3, 2023, 04:15
Default control the temperature every 0.5s
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chenfuqiang
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Hi geth03,
Thank you very much for your reply. I modified chtMultiRegionFoam/solid/solveSolid.H.
Please find it below:
Code:
{
    while (pimple.correctNonOrthogonal())
    {
//control point
fvMesh& mesh = solidRegions[i];
point position = point(0.0425,0.021,0.135);
label mycell = mesh.findCell(position);
const Foam::volScalarField& T = mesh.lookupObject<Foam::volScalarField>("T");
scalar Tcell = T[mycell];
reduce(Tcell, maxOp<scalar>());
//
if (Tcell < 340)
{
        fvScalarMatrix hEqn
        (
            fvm::ddt(betav*rho, h)
          - (
                thermo.isotropic()
              ? fvm::laplacian(betav*thermo.alpha(), h, "laplacian(alpha,h)")
              : fvm::laplacian(betav*taniAlpha(), h, "laplacian(alpha,h)")
            ) + poy    //poy is volScalarField.
          ==
            fvOptions(rho, h)
        );      
}
else
{
        fvScalarMatrix hEqn
        (
            fvm::ddt(betav*rho, h)
          - (
                thermo.isotropic()
              ? fvm::laplacian(betav*thermo.alpha(), h, "laplacian(alpha,h)")
              : fvm::laplacian(betav*taniAlpha(), h, "laplacian(alpha,h)")
            ) 
          ==
            fvOptions(rho, h)
        );     
}
    }
}

hEqn.relax();
fvOptions.constrain(hEqn);
hEqn.solve();
fvOptions.correct(h);
thermo.correct();

Info<< "Min/max T:" << min(thermo.T()).value() << ' '
    << max(thermo.T()).value() << endl;
And I have another problem. In the controlDict file , the deltaT is 0.01. So the above code judges every 0.01s. It is too frequent. I want to control the temperature every 0.5s.
I use:
Code:
if (runTime.value()==0 or fmod(runTime.value(), 0.5) ==0)//Multiple of 0.5
{the above code}
but this only run hEqn at 0s,0.5s,1s,1.5s... ...
I dont know how to judge every 0.5s instead of judge by the deltaT.

Thank you in advance!
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Old   January 3, 2023, 09:41
Default Has solved
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Has solved!Do you have a better solution? Please tell me!
Code:
fvMesh& mesh = solidRegions[i];
point position = point(0.0425,0.021,0.135);
label mycell = mesh.findCell(position);
const Foam::volScalarField& T = mesh.lookupObject<Foam::volScalarField>("T");
//scalar Tcell = VGREAT;
 //if (mycell != -1)
//{
 scalar Tcell = T[mycell];
//}
reduce(Tcell, maxOp<scalar>());
bool flag ;
for (double tt = 0;tt<100;tt=tt+0.5)
{
if (tt <= runTime.value() < tt+0.5)
  {
  if (Tcell > 310 and runTime.value() == tt)
  {flag = true;}
  if (Tcell <= 310 and runTime.value() == tt)
  {flag = false;}
  }
}

if (flag)
{
        fvScalarMatrix hEqn
        (
            fvm::ddt(betav*rho, h)
          - (
                thermo.isotropic()
              ? fvm::laplacian(betav*thermo.alpha(), h, "laplacian(alpha,h)")
              : fvm::laplacian(betav*taniAlpha(), h, "laplacian(alpha,h)")
            )
          ==
            fvOptions(rho, h)
        );

        hEqn.relax();

        fvOptions.constrain(hEqn);

        hEqn.solve();

        fvOptions.correct(h);
}
if (!flag)
{
        fvScalarMatrix hEqn
        (
            fvm::ddt(betav*rho, h)
          - (
                thermo.isotropic()
              ? fvm::laplacian(betav*thermo.alpha(), h, "laplacian(alpha,h)")
              : fvm::laplacian(betav*taniAlpha(), h, "laplacian(alpha,h)")
            ) + poy_recv
          ==
            fvOptions(rho, h)
        );

        hEqn.relax();

        fvOptions.constrain(hEqn);

        hEqn.solve();

        fvOptions.correct(h);
}
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control point, control valve, heat equation, heat source term, value of interest

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