[artymk4]

Is it possible to write data at specified times (timesteps) instead of fixed intervals?
I want to output data multiple times only at the end of simulation. If I wanted to write data only at the very last time step, I could do this:

endTime         4000;
deltaT          1;
writeControl    timeStep;
writeInterval   4000;

But I want to write data at time steps 3970, 3980, 3990, 4000. I know I could do this with purgeWrite:

endTime         4000;
deltaT          1;
writeControl    timeStep;
writeInterval   10;
purgeWrite      4;

But this way my simulation would take much more time because of useless writing every 10 time steps from the beginning (400 times instead of 4).


There's another option, to end simulation at time 3970 with writeInterval 3970 so I get only one output. And then starting simulation again from latest time with writeInterval 10 and endTime 4000. But this is not ideal because it's not automatic, I need to change controlDict during simulation.
My solution would be this:

endTime         4000;
deltaT          1;
writeControl    timeStep;
writeInterval   (3970 3980 3990 4000);

but it's not working because writeInterval needs to be scalar. Maybe this can be suggestion for next update. Or can I modify OpenFOAM so it will accept more values, not only one interval. But I have no idea how to do that.

[dybuk]

You can use systemCall function object and second controlDictfile

For eg.
controlDict

endTime         4000;
deltaT          1;
writeControl    timeStep;
writeInterval   3970;

newControlDict

endTime         4000;
deltaT          1;
writeControl    timeStep;
writeInterval   10;

and in systemCall function object setup

writeCalls
        (
            "cp system/newControlDict system/controlDict"
        );

In time step 3970 you will save the result and change the write interval to 10 so you will end with saved time step 3970 3980 3990 4000

[artymk4]

Originally Posted by dybuk

You can use systemCall function object and second controlDictfile

For eg.
controlDict

endTime         4000;
deltaT          1;
writeControl    timeStep;
writeInterval   3970;

newControlDict

endTime         4000;
deltaT          1;
writeControl    timeStep;
writeInterval   10;

and in systemCall function object setup

writeCalls
        (
            "cp system/newControlDict system/controlDict"
        );

In time step 3970 you will save the result and change the write interval to 10 so you will end with saved time step 3970 3980 3990 4000

Thanks, I didn't know about function systemCall. However I'm using foam-extend-4.0 which lacks this function. I got error Unknown function type systemCall

[jherb]

Have you added the library to the run?

functionObjectLibs ( "libsystemCall.so" );

See: https://openfoamwiki.net/index.php/T...ect_systemCall


Actually, you also need this lib:

libs ( "libutilityFunctionObjects.so" );

[mAlletto]

I'll just post the solution I've found just in case someone is interested: I used OF1912 and there you have the function object timeActivatedFileUpdate. Where you basically can update a given file to a specific time step. So each time one wants a different timestep to written the fields out one can update the control dict:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v1912                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

application     rhoPimpleFoam;

startFrom       latestTime;

startTime       0;

stopAt          endTime;

endTime         0.26;

deltaT          2e-6;
adjustTimeStep  yes;

maxCo           3.0;


writeControl    adjustable;

#include "writeInterval"

//writeInterval   0.01;

purgeWrite      0;

writeFormat     ascii;

writePrecision   8;

writeCompression off;

timeFormat      general;

timePrecision   6;

runTimeModifiable true;

functions
{
    #includeFunc MachNo
    #includeFunc residuals
    
    fileUpdate1
    {
        type              timeActivatedFileUpdate;
        libs              ("libutilityFunctionObjects.so");
        writeControl      timeStep;
        writeInterval     1;
        fileToUpdate      "<system>/writeInterval";
        timeVsFile
        (
            (-1   "<system>/writeInterval.00")
            (0.002   "<system>/writeInterval.01")
            (0.005 "<system>/writeInterval.02")
            (0.011 "<system>/writeInterval.03")
            (0.022 "<system>/writeInterval.04")
            (0.028 "<system>/writeInterval.05")
            (0.08 "<system>/writeInterval.06")
            (0.09 "<system>/writeInterval.07")
            (0.1 "<system>/writeInterval.08")
            (0.11 "<system>/writeInterval.09")
            (0.153 "<system>/writeInterval.10")
            (0.16   "<system>/writeInterval.11")
            (0.17 "<system>/writeInterval.12")
            (0.18 "<system>/writeInterval.13")
            (0.23 "<system>/writeInterval.14")
            (0.24 "<system>/writeInterval.15")
            (0.25 "<system>/writeInterval.16")
        );
    }


}

The files writeInterval contain the desired time step, e.g. /writeInterval.16 contains the entry:


writeInterval 0.252614931093667;


In this way I could achieve that the fields are written out at irregular time steps.

[sjohn2]

Hi can you post your writeinterval file?
is it valid for foundation version?

[mAlletto]

I don't know if it is valid for the foundation version. The file contains simply the entries

writeInterval 0.252614931093667;

[anhkenyt]

Originally Posted by dybuk

You can use systemCall function object and second controlDictfile

For eg.
controlDict

endTime         4000;
deltaT          1;
writeControl    timeStep;
writeInterval   3970;

newControlDict

endTime         4000;
deltaT          1;
writeControl    timeStep;
writeInterval   10;

and in systemCall function object setup

writeCalls
        (
            "cp system/newControlDict system/controlDict"
        );

In time step 3970 you will save the result and change the write interval to 10 so you will end with saved time step 3970 3980 3990 4000

Hi foamers,
I want to write data only at the 3 final steps (98 99 100)
Thank dybuk for your interesting answers, but when I use systemCall as you said.
However, nothing happens. Anybody can help me?
This is controlDict

startFrom       startTime;
startTime       0;
stopAt          endTime;
endTime         0.0001;//0.007; //0.00052;//0.002; //1 first 0.00052;
deltaT          0.000001; //0.0000005;
writeControl    timeStep;//adjustableRunTime;//
writeInterval   96;
purgeWrite      0;
writeFormat     ascii;
writePrecision  6;
writeCompression off;
timeFormat      general;
timePrecision   6;
runTimeModifiable true;
adjustTimeStep	no;
maxCo		0.9;
maxDeltaT	0.1;
writeCalls
(
	"cp system/newControlDict system/controlDict" 
);

and newControlDict

startFrom       startTime;
startTime       0;
stopAt          endTime;
endTime         0.0001;// 0.007; //0.00052;//0.002; //1 first 0.00052;
deltaT          0.000001; //0.0000005;
writeControl    timeStep;//adjustableRunTime;//
writeInterval   1;
purgeWrite      0;
writeFormat     ascii;
writePrecision  6;
writeCompression off;
timeFormat      general;
timePrecision   6;
runTimeModifiable true;
adjustTimeStep	no;
maxCo		0.9;
maxDeltaT	0.1;
libs ( "libutilityFunctionObjects.so" );

When running has done just have data at 96 steps.