[Albertine]

Good morning,
I'm trying to run some offline function objects using the command foamPostProcess after the simulation is completed.

I've written the functions looking a the documents into etc/postProcessing.
I managed to add a probe to get the pressure, but I'm struggling to get forces.

My question is: is it possible to get forces offline?

If yes can you help me?

This is my function and the consequent error:

forces_splitter
{

type forces;
libs ("libforces.so");

writeControl timeStep;
writeInterval 1;



patches (splitter);

rhoInf 1.225;

CofR (0 0 0)>;

pitchAxis (1 0 0);

rho rhoInf;
}

--> FOAM FATAL ERROR:
Could not find U, p

From function void Foam::functionObjects::forcesBase::initialise()
in file forcesBase/forcesBase.C at line 186.

FOAM exiting

[JNSN]

from the documentation (https://doc.cfd.direct/openfoam/user...processing-cli):
*****************************************
This returns the following error message.
--> FOAM FATAL IO ERROR:
request for volVectorField U from objectRegistry region0 failed

The error message is telling the user that the velocity field U is not loaded. For the function to work, both the field needs to be loaded using the -field option as follows.

foamPostProcess -fields "(p U)" -func wallShearStress

Even loading relevant fields, the post-processing fails with the following message.
--> FOAM FATAL ERROR:
Unable to find turbulence model in the database

The message is telling us that the foamPostProcessutility has not constructed the necessary models, i.e. a turbulence model, that the incompressibleFluid solver module used when running the simulation. This is a situation where we need to post-process (as opposed to run-time process) using the -solver option modelling will be available that the post-processing function needs.

foamPostProcess -solver incompressibleFluid -func wallShearStress

Note that no fields need to be supplied, e.g. using ”-field U”, because incompressibleFluid module constructs and stores the required fields. Functions can also be selected by the #includeFunc directive in functions file, instead of the -func option.
*************************************

[Albertine]

Originally Posted by JNSN

from the documentation (https://doc.cfd.direct/openfoam/user...processing-cli):
*****************************************
This returns the following error message.
--> FOAM FATAL IO ERROR:
request for volVectorField U from objectRegistry region0 failed

The error message is telling the user that the velocity field U is not loaded. For the function to work, both the field needs to be loaded using the -field option as follows.

foamPostProcess -fields "(p U)" -func wallShearStress

Even loading relevant fields, the post-processing fails with the following message.
--> FOAM FATAL ERROR:
Unable to find turbulence model in the database

The message is telling us that the foamPostProcessutility has not constructed the necessary models, i.e. a turbulence model, that the incompressibleFluid solver module used when running the simulation. This is a situation where we need to post-process (as opposed to run-time process) using the -solver option modelling will be available that the post-processing function needs.

foamPostProcess -solver incompressibleFluid -func wallShearStress

Note that no fields need to be supplied, e.g. using ”-field U”, because incompressibleFluid module constructs and stores the required fields. Functions can also be selected by the #includeFunc directive in functions file, instead of the -func option.
*************************************

Thank you very much!!