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Unsteady kE with scalar transport - Outlet-geometry heavely effects scalar transport

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Old   June 25, 2009, 03:00
Default Unsteady kE with scalar transport - Outlet-geometry heavely effects scalar transport
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Christian Andersen
Join Date: Mar 2009
Location: Aalborg, Denmark
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Hi OpenFoamers,
I have a problem getting my custom OpenFOAM solver to transport scalar specie to the outlet!

I have tried several things:
1. It works with steadyState kE, solution converges and scalar is trasported.
2. It works as unsteady - if the outlet is a 80 tube and a pressure condition at the end! (no big opening)
3. I have tried symmetry BC, outletInlet BC and pressure Outlet BC for a square box
4. I have tried pressure Outlet BC for a half sphere.
5. I dont know why, but I have seen new variables in the time-folders U_0 and scalar_0 - why is there suddenly thees parallel files?
6. Residuals for specie are 1E-5
7. The falty solution seems to be caused by my outlet?

My custom code is like this:

fvScalarMatrix CH4Eqn
(
fvm::ddt(CH4)
+fvm::div(phi, CH4)
- fvm::laplacian(turbulence->nut()/0.7,CH4)
);
CH4Eqn.solve();

I use QUICK scheme for div and Euler for timestep.

I have attached jpegs of the current solutions.

Any suggestions?

BR Christian
Attached Images
File Type: jpg specie_ss_vector.jpg (23.7 KB, 14 views)
File Type: jpg trans_specie_vector.jpg (16.0 KB, 10 views)
File Type: jpg trans_Umag_vector1.jpg (18.4 KB, 6 views)
File Type: jpg pipe_trans_specie_vector.jpg (8.9 KB, 6 views)
File Type: jpg Umag.jpg (14.9 KB, 6 views)

Last edited by christian_andersen; June 25, 2009 at 05:56. Reason: The outlet was not visible in the first pictures.
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