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GGI function ggiCheck in OF 15dev

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Old   February 3, 2009, 15:50
Default Dear All, I am simulating a
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Louis Gagnon
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Dear All,

I am simulating a mixer type of problem using the 1.5-dev GGI mesh and while testing the different values for phi within the ggiCheck function in controlDict I realised that I could remove the whole ggiCheck function and would get the exact same results.

I am using the 1.5-dev build of Jan. 6.

Am I missing something about the ggiCheck function?

Here is what I have used so far:

functions
(
ggiCheck
{
// Type of functionObject
type ggiCheck;
phi phi;
// Where to load it from (if not already in solver)
functionObjectLibs ("libsampling.so");
}
...
)

thanks for any clarification!

-Louis
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Old   February 3, 2009, 16:12
Default To answer myself, these are on
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Louis Gagnon
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To answer myself, these are only checks that report differences to the commandline. Thus, the results are not affected.

I was able to have all 4 differences given as output during runtime with



functions
(
ggiCheck
{
// Type of functionObject
type ggiCheck;
phi weightingFactors;

// Where to load it from (if not already in solver)
functionObjectLibs ("libsampling.so");
}

ggiCheck2
{
// Type of functionObject
type ggiCheck;

phi differenceFactors_;
// Where to load it from (if not already in solver)
functionObjectLibs ("libsampling.so");
}
ggiCheck3
{
// Type of functionObject
type ggiCheck;
phi phi;

// Where to load it from (if not already in solver)
functionObjectLibs ("libsampling.so");
}

ggiCheck4
{
// Type of functionObject
type ggiCheck;

phi meshPhi;
// Where to load it from (if not already in solver)
functionObjectLibs ("libsampling.so");
}
...
)


which yields


Courant Number mean: 0.0112644452679 max: 0.502069123018
deltaT = 4.44282049584e-06
GGI pair (insideSlider, outsideSlider) : 40.5709869507 35.4281942396 Diff = 75.9991811903 or 187.323964494 %
GGI pair (insideSlider, outsideSlider) : 60408.2865474 60409.0436563 Diff = 120817.330204 or 200.00125332 %
GGI pair (insideSlider, outsideSlider) : 0.0665444451388 0.0664723050084 Diff = -6.22481027305e-06 or 0.00935436498128 %
GGI pair (insideSlider, outsideSlider) : 4.03433199548e-05 0 Diff = -1.32764702777e-14 or 3.2908720186e-08 %
Time = 0.000124117


Should I be worried about a 200% difference of weighting and difference factors?


my apologies for the double-post.

-Louis
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Old   February 3, 2009, 20:44
Default Hello Louis, The ggiCheck f
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Martin Beaudoin
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Hello Louis,

The ggiCheck functionObject was developped for the purpose of evaluating if the GGI is conservative or not. And from your results, we can see that the phi unbalance is quite acceptable.

The surface fields differenceFactors_ and weightingFactors evaluated from the class surfaceInterpolation have nothing to do with the GGI or the GGI weighting factors.

So using ggiCheck with those 2 surfaceFields basically generates useless information.

Martin
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Old   February 3, 2009, 21:08
Default Thank you very much for your c
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Louis Gagnon
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Thank you very much for your clarification Martin.

Regards,

-Louis
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