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-   -   Density changes in the solid part. (https://www.cfd-online.com/Forums/fluent/188404-density-changes-solid-part.html)

Audrius May 29, 2017 15:59

Density changes in the solid part.
 
Hello colleagues,

I would like to perform Fluent validation for natural circulation phenomena with conjugate heat transfer. For the beginning, I created a simple geometry, which consists of two parts: fluid and solid zones. In the bottom part of fluid zone there is water, in the top there is air. The solid part is made from aluminium. After first iteration I noticed, that density of aluminium plate is not the same throughout the solid plate. In the outside of aluminium plate the density is 0 kg/m3. This should not be. When I use the same geometry, the same mesh for single flow, for example, the density of plate is good. I do not understand why what is. I think it's related to the VOF model.

Maybe You can explain where I am doing mistake, please?

https://scontent.fkun1-1.fna.fbcdn.n...f1&oe=59B11FE6

LuckyTran May 29, 2017 23:46

Check the boundary conditions for the aluminum and see if you specified a funny phase. The "density" is the bulk density which is the sum of phase-densities.

In multi-phase problems, it's always a good idea to have a plot of the phase fractions.

Audrius May 30, 2017 06:45

Here presented properties of aluminium:
https://scontent.fbud2-1.fna.fbcdn.n...e1&oe=59AAEE1B

Air density:
https://scontent.fbud2-1.fna.fbcdn.n...d7&oe=59E45BA6

Air volume fraction:
https://scontent.fbud2-1.fna.fbcdn.n...12&oe=59BA4393

Water density:
https://scontent.fbud2-1.fna.fbcdn.n...aa&oe=59E7F31D

Water volume fraction:
https://scontent.fbud2-1.fna.fbcdn.n...4b&oe=59E2FE8E

And here is density contour in Fluent:
https://scontent.fbud2-1.fna.fbcdn.n...5b&oe=59B57F0D

Why in the Fluent I see good density, but in CFD-Post with changes?:confused:

mcuneytk June 7, 2021 06:49

hi;
did you find the solution ?
I have similar problem. I created a solid zone for wall and after initialization, I see that density of solid zone is zero even I entered constant value in materials section.
Fluid zone looks ok.

Quote:

Originally Posted by LuckyTran (Post 650828)
Check the boundary conditions for the aluminum and see if you specified a funny phase. The "density" is the bulk density which is the sum of phase-densities.

In multi-phase problems, it's always a good idea to have a plot of the phase fractions.



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