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Averaging in channelFoam

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Old   September 30, 2010, 09:10
Default Averaging in channelFoam
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Steven van Haren
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Dear Foamers,

I am trying to start the averaging after a certain time in my simulation. Acoording to the wiki this should be possible using the keyword "after":http://openfoamwiki.net/index.php/Co...unctionObjects

However, I can not get it to work.

Here is my function in the controlDict file:

functions
{
fieldAverage1
{
type fieldAverage;
functionObjectLibs ( "libfieldFunctionObjects.so" );
cleanRestart true;
enabled true;
outputControl outputTime;
after 5/1.8e-4;//5 non-dimensional time-units for Retau=180

fields
(
U
{
mean on;
prime2Mean on;
base time;
}

p
{
mean on;
prime2Mean on;
base time;
}
);

}
}

I have tried various different syntaxes for the keyword after but every time the program starts to average immidiately. Does anyone have an idea about how to use the keyword "after" correctly?
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Old   September 30, 2010, 14:33
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Bernhard Gschaider
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Quote:
Originally Posted by stevenvanharen View Post
Dear Foamers,

I am trying to start the averaging after a certain time in my simulation. Acoording to the wiki this should be possible using the keyword "after":http://openfoamwiki.net/index.php/Co...unctionObjects

However, I can not get it to work.

Here is my function in the controlDict file:

functions
{
fieldAverage1
{
type fieldAverage;
functionObjectLibs ( "libfieldFunctionObjects.so" );
cleanRestart true;
enabled true;
outputControl outputTime;
after 5/1.8e-4;//5 non-dimensional time-units for Retau=180

fields
(
U
{
mean on;
prime2Mean on;
base time;
}

p
{
mean on;
prime2Mean on;
base time;
}
);

}
}

I have tried various different syntaxes for the keyword after but every time the program starts to average immidiately. Does anyone have an idea about how to use the keyword "after" correctly?
The fieldAverage-functionObject is NOT part of the simpleFunction-Objects and therefor does things differently (probably ignores "after"). One of the OF-tutorials (can'T remember which) uses it. Have a look there how it is done
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Old   October 1, 2010, 07:53
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Steven van Haren
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Ok, thanks.

I'm now trying to rebuild the library for fieldAverage so that it can use this functionality.

I will look in the simplefunction objects which function has this feature and rebuild it using that as an example.
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Old   October 4, 2010, 10:05
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Steven van Haren
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Quote:
Originally Posted by gschaider View Post
The fieldAverage-functionObject is NOT part of the simpleFunction-Objects and therefor does things differently (probably ignores "after"). One of the OF-tutorials (can'T remember which) uses it. Have a look there how it is done
Dear Bernhard,

Ok, I got it working. Mainly thanks to your source-code for simpleFunctionObject.
So thank you for that.

I have another question, how do you control the calling of the member functions from the channelFoam? In the comments you give some information about the calling of "start" and "execute". But for the fieldAverage function the channelFoam calls the "constructor", but also "execute" and "write". How can you manipulate this? For instance add a new member function to the class which is called from the solver?

Testing the "libsampling.so" library it appears that the "execute" function is not called by the solver, but only the "write" function.

Thanks in advance,

Regards,

Steven

Last edited by stevenvanharen; October 5, 2010 at 06:24.
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Old   October 5, 2010, 12:41
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Bernhard Gschaider
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Quote:
Originally Posted by stevenvanharen View Post
Dear Bernhard,

Ok, I got it working. Mainly thanks to your source-code for simpleFunctionObject.
So thank you for that.

I have another question, how do you control the calling of the member functions from the channelFoam? In the comments you give some information about the calling of "start" and "execute". But for the fieldAverage function the channelFoam calls the "constructor", but also "execute" and "write". How can you manipulate this? For instance add a new member function to the class which is called from the solver?

Testing the "libsampling.so" library it appears that the "execute" function is not called by the solver, but only the "write" function.

Thanks in advance,

Regards,

Steven
Hi Steve!

Just a pointer for further research:
http://foam.sourceforge.net/doc/Doxy...2ab372ca5c257b
execute of all functionObjects get called whenever the time is increased. write is not in the interface of the functionObject http://foam.sourceforge.net/doc/Doxy...ionObject.html but a speciality of the simpleFunctionObjects

You can add any member function to your subclass, but only those in the standard-interface will be called at special times. So your own methods must be called from one of those. Not much you can do about it without rewritting the Time-class (which I wouldn'T advise)

Bernhard
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Old   October 6, 2010, 08:04
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Steven van Haren
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Quote:
Originally Posted by gschaider View Post
Hi Steve!

Just a pointer for further research:
http://foam.sourceforge.net/doc/Doxy...2ab372ca5c257b
execute of all functionObjects get called whenever the time is increased. write is not in the interface of the functionObject http://foam.sourceforge.net/doc/Doxy...ionObject.html but a speciality of the simpleFunctionObjects

You can add any member function to your subclass, but only those in the standard-interface will be called at special times. So your own methods must be called from one of those. Not much you can do about it without rewritting the Time-class (which I wouldn'T advise)

Bernhard
Ok, thanks! Indeed found the call to execute in the time class. Now at least I am sure about what is going on.

Thank you very much for your help!

Regards,

Steven
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