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Difference between exact value and calculated value

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Old   August 18, 2011, 08:31
Default Difference between exact value and calculated value
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I want to calculate Teps of the the following equation:

T0 (1 + Teps) = T

T0 is the exact solution and T the solution calculated by OpenFOAM in each time step.

For the internalField it works. And also if an boundary patch is defined as type inletOutlet with an uniform inletValue and an uniform value it works too. But if an patch is defined as type zeroGradient or type fixedValue with an uniform value, the calculation of Teps seems not to work. Then the mentioned patches of the boundary field of Teps look the same as the boundary fields in T.
Does anybody know how I can get the right values of these patches?
I want to calculate the same for p, rho and U.
Or are there already applications in OpenFOAM, which calculate the difference between an exact value and the values calculated by OpenFOAM?

Thanks in advance,
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Old   August 19, 2011, 05:19
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Eugene de Villiers
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The trick is to create your result field independent of the input fields so that it uses a "calculated" type boundary everywhere. Then the assignment should work fine.

Something like:

volScalarField Teps
blah blah blah
dimensionedScalar("Teps", T.dimensions(), 0.0)

Teps = some functions of T and T0
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Old   August 19, 2011, 06:10
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Hrvoje Jasak
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Did you call


after updating the internal field?

Hrvoje Jasak
Providing commercial FOAM/OpenFOAM and CFD Consulting:
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