[Vylnius Mante]

Hello to everyone reading this thread,

I try to perform a DNS simulation of an incompressible flow by using the pimple algorithm in OpenFOAM. As the resolution of the computational mesh is too high to save all the data at all the points, we decided to save only the data in a restricted area of the domain by using the probe function (writen in the controlDict file). Everything seems to work perfectly except that the use of the probe function seems to slow down the computation and limit the scalability of the computation, even with one probe. It seems that the probe function is called and search the probe locations in the domain at every time step even if the data are saved in the right post-processing files every two time steps.

Does anyone know how to avoid the call of the probe function at every time step but only for the times when it is necessary to save the data ?

Thank you in advance.

[Yann]

Hello,

I don't know if this is the actual problem you are facing, but do you know there are 2 parameters to control function objects? writeControl and executeControl. If you didn't define executeControl the default behavior would be to execute the function every time step even if writeControl is set to write data every 2 time steps.

https://doc.openfoam.com/2306/tools/...bject-controls

I hope this helps,
Yann

[Vylnius Mante]

Hello Yann,

First, thank you for your quick answer.

It seems that the computation is faster by adding the lines executeControl and executeInterval.
But I have always the same warning:

--> FOAM Warning :

From function virtual void Foam:robes::findElements(const Foam::fvMesh&)

in file probes/probes.C at line 117

Did not find location (0.233625 0.003625 0.11775) in any cell. Skipping location.


I know why I have this warning: it is because I have a movable object in the fluid domain whose position changes with time while the probe locations remain unchanged during the computation. Therefore, some probes lie in the movable object and no data can be considered in these positions. So, I am ok with the nature of the warning and I can deal with the "data" stored in the void (I treat them in a Python post-processing code as "not a number") but the fact that it is diplayed every time step seems to me that the probe function works yet at every time step.

Am I wrong ?

Thank you in advance.

[Yann]

Hello,

If you get the warning at every time step it indeed looks like the function is still executed.

Could you please share your function definition?
Have you specified an executeInterval?

Yann

[Vylnius Mante]

Helo,

Below, the function written in the controlDict file:

probes_part_0
{
type probes;
functionObjectLibs ("libsampling.so");
fields
(
U
p
//scalar_injection

//gas_sky
);
executeControl adjustableRunTime;
executeInterval 0.025;
writeControl adjustableRunTime;
writeInterval 0.025;
probeLocations
(
(-0.007125 -0.121625 0.11625)
(-0.006375 -0.121625 0.11625)
(-0.005625 -0.121625 0.11625)
(-0.004875 -0.121625 0.11625)
...
);
}

Vylnius

[Yann]

Hello Vylnius,

What OpenFOAM version are you using ?

[Vylnius Mante]

OpenFOAM version 9

[Yann]

OK, I was asking because functionObjectLibs ("libsampling.so"); is an old syntax and old OpenFOAM versions used evaluateControl and outputControl rather than executeControl and writeControl, respectively.

But On OpenFOAM-9 it should definitively be executeControl and writeControl.

I don't know if this is a specific issue for the probes function object.