[bingchuan]

Hi All,

I want to get the integral of the gradient of a variable (e.g. Temperature) over a face during doing an unsteady simulation.

1. First, I computed the gradient of the variable by adding the following code into the main function of the solver, then it is compiled.

         volVectorField gradT(fvc::grad(T));

 

         volScalarField gradTx

         (

             IOobject

             (

                 "gradTx",

                 runTime.timeName(),

                 mesh,

                 IOobject::NO_READ,

                 IOobject::AUTO_WRITE

             ),

             gradT.component(vector::X)

         );

 

         volScalarField gradTy

         (

             IOobject

             (

                 "gradTy",

                 runTime.timeName(),

                 mesh,

                 IOobject::NO_READ,

                 IOobject::AUTO_WRITE

             ),

             gradT.component(vector::Y)

         );

 

         volScalarField gradTz

         (

             IOobject

             (

                 "gradTz",

                 runTime.timeName(),

                 mesh,

                 IOobject::NO_READ,

                 IOobject::AUTO_WRITE

             ),

             gradT.component(vector::Z)

         );

The gradTx, gradTy and gradTz are wrote in the time series directories. Of course I can get the integral of gradT over a face in the post-process software (e.g. paraView). However, since the computational domain is large, it is inpossilbe to to write gradT in small time interval. So I have to find another way out.

2. I planed to use the function objects. I put the patchIntegrate file in the system directory of my case, which was included by the controlDict file. The item fields in the patchIntegrate file are defined as

fields (U  gradT)

or

fields (U gradTx)

However, only integral of U over the patch were outputted successfully. No integral of gradT or gradTx such data was wrote.

3. Then I tried the singleGraph in the same way as patchIntegrate.

No gradT or gradTx such data was wrote along the line I defined neither.

Is there anyone knows how to solve this problem or anyone has better strategy to do this? Thank you very much.

kind regards,
Bingchuan

[bingchuan]

Can anyone bring me a ray of light?
many Thanks.

[agustinvo]

Hi

can you show us the case folder? At least, the controlDict file.

it is inpossilbe to to write gradT in small time interval

what do you mean there?

[bingchuan]

Dear Agustin,

Thanks for your reply.

Below is the information of my transient simulation.
1. Code added into the main function of the solver

....
  volVectorField gradT(fvc::grad(T));

 

         volScalarField gradTx

         (

             IOobject

             (

                 "gradTx",

                 runTime.timeName(),

                 mesh,

                 IOobject::NO_READ,

                 IOobject::AUTO_WRITE

             ),

             gradT.component(vector::X)

         );
....

2. The controlDict file:

....

timeFormat      general;

timePrecision   6;

runTimeModifiable true;

adjustTimeStep  no;

maxCo           0.5;

// ************************************************************************* //
functions
{
/#includeFunc patchIntegrate
}

3. The patchIntegrate file

name   Mypatch;
fields ( U T gradT gradTx);
operation areaIntegrate;

type            surfaceRegion;
libs            ("libfieldFunctionObjects.so");
regionType  patch;

writeControl    timeStep;
writeInterval   1;
...

Goal: output the integral of fields U, T, gradT and gradTx over the given patch at every timestep using the function object patchIntegrate.

Issue: Integrals of fields U and T at every timestep have been outputted successfully. However, It is failed to output the integral of gradT and gradTx.

log information: FOAM warning: From function Foam::label Foam::sampledSets::classifyFields() in file sampledSetsGrouping.C at line 140 cannot find registered field matching gradT. (The same warning for gradTx)

Thanks.

Bests,
Bingchuan