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-   -   Calculation of the deformation rate (http://www.cfd-online.com/Forums/openfoam-solving/62786-calculation-deformation-rate.html)

titio March 19, 2009 13:50

Calculation of the deformation rate
 
Hi Foamers,

i am currently trying to model non-newtonian flow using OpenFoam and based on the PISO as implemented in the icoFoam solver, and I stumbled in the calculation of the deformation rate. At least so I think because the results I am getting for a comparison case with an a analytical solution.

I am calculating thye deformation rate using the following formula

DR=DU+DUT

where DU=fvc::grad(U) and DUT=DU.T(). DU, DUT and DR are defined as tensor fields, that were all initialized in the createFields.h file, although they are not defined in the vector and tensorial fields defined in the 0 folder. The code I added to the file is the following

volTensorField DU
(
IOobject
(
"DU",
runTime.timeName(),
mesh,
IOobject::NO_READ,
IOobject::NO_WRITE
),
fvc::grad(U)
);

volTensorField DUT
(
IOobject
(
"DUT",
runTime.timeName(),
mesh,
IOobject::NO_READ,
IOobject::NO_WRITE
),
DU.T()
);

volTensorField DR
(
IOobject
(
"DR",
runTime.timeName(),
mesh,
IOobject::NO_READ,
IOobject::NO_WRITE
),
DU + DUT
);

DU, DUT and DR are all recalculated in all iterations of PISO algorithm. Thus, all formulas are repeated in the main code of the solver I developed.

Is the code that I presented O.K? When I compared predicted with analytical results, it looks like I not getting the values of the deformation rate I should have.

Anyone have some idea how to properly represent the tensor fields, and to calculate the deformation rate I woulf greatly appreciate.

Titio

kerstin March 22, 2009 09:45

Check this thread
http://www.cfd-online.com/Forums/ope...1-vs-15-a.html
The search function of the forum is your friend ;-)


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