[FlyBob91]

Hello to all,
i want to extract the velocity profile at the outlet of my channel for using it as initial condition in another simulation.
My question is: how can i extract it?

The only way i found till now is the "readFields" tool but i don't know how to adapt it for the profile over a boundary. Can someone explain me how to modify it?

readFields1
{
    type        readFields;
    functionObjectLibs ("libfieldFunctionObjects.so");
    ...
    fields      (U p);
}

If there was another way to do what i need it would be fantastic in the same manner.

Thank for help and your time.

Roberto

[danielbanos10]

There is a tool, that seems that is what you are searching for, MapFields
https://openfoamwiki.net/index.php/MapFields

[tiam]

Originally Posted by FlyBob91

Hello to all,
i want to extract the velocity profile at the outlet of my channel for using it as initial condition in another simulation.
My question is: how can i extract it?

The only way i found till now is the "readFields" tool but i don't know how to adapt it for the profile over a boundary. Can someone explain me how to modify it?

readFields1
{
    type        readFields;
    functionObjectLibs ("libfieldFunctionObjects.so");
    ...
    fields      (U p);
}

If there was another way to do what i need it would be fantastic in the same manner.

Thank for help and your time.

Roberto

Hi!
What do you mean by "profile"? If it is a surface of a line -- use the sample utility.

[FlyBob91]

Originally Posted by tiam

Hi!
What do you mean by "profile"? If it is a surface of a line -- use the sample utility.

hello tiam, thank you for your reply.
For profile i mean the value of the velocity field for every cells at the output.

Regards,
Roberto

[tiam]

Originally Posted by FlyBob91

hello tiam, thank you for your reply.
For profile i mean the value of the velocity field for every cells at the output.

Regards,
Roberto

Hi Roberto,
If you can live with using face-values at the outlet instead, use the sample utility for surface-sampling.

If you really need the cell values, you might have to code your self.
It is possible to grab the cell-center value associated with the patch-face, so it be doable. Explor the fvPatchField classes and ralated things for that.

Best,
Timofey

[chpjz0391]

Originally Posted by FlyBob91

hello tiam, thank you for your reply.
For profile i mean the value of the velocity field for every cells at the output.

Regards,
Roberto

Hi Roberto,
I think you can achieve this by using ParaView. Using the "select cells on" function, then you can select the cells on the outlet. Then you can read the data on the cells which you chose and output the data on the cells.

Regards,
Ping

[victorious_BIG]

This code snippet will extract the outlet velocity of a case on the patch named "outlet" and then write the output formatted as a fixedValue BC for a velocity inlet. Just copy and past the buffer output into your 0/U file.

Paste the following into the bottom of your solver and compile (wmake):

const label& patchID = mesh.boundaryMesh().findPatchID("outlet");
const fvPatch& outPatch = mesh.boundary()[patchID];
const fvPatchField<vector>& outU =
outPatch.lookupPatchField<volVectorField, vector>("U");

const vectorField outUvalues = outU.patchInternalField();

Info << " type fixedValue;" << endl;
Info << " value nonuniform List<vector>" << endl;
Info << " " << outUvalues.size() << endl;
Info << " (" << endl;
forAll(outUvalues,vecI)
{
Info << " (" << outUvalues[vecI][0] << " 0 0)" << endl;
}
Info << " );" << endl;