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-   -   Cyclone with Lots of Porous Jumps = Divergence (https://www.cfd-online.com/Forums/fluent/113995-cyclone-lots-porous-jumps-divergence.html)

 recepky March 3, 2013 04:26

Cyclone with Lots of Porous Jumps = Divergence

Hi,

I have a problem that contains a cyclone geom. and has lots of porous jumps in the center.

I meshed the entire geometry with hexa mesh and I ended up with a good quality mesh, only some complex sections of the geometry has tetrahedra mesh.

I solve the problem using Reynold Stress Model, without porous jumps, but when I set the porous jumps and set the constant values for it and run calculation after 50 iteration solver become diverged. :confused: What I am doing wrong?

 A CFD free user March 4, 2013 15:09

Quote:
 Originally Posted by recepky (Post 411133) Hi, I have a problem that contains a cyclone geom. and has lots of porous jumps in the center. I meshed the entire geometry with hexa mesh and I ended up with a good quality mesh, only some complex sections of the geometry has tetrahedra mesh. I solve the problem using Reynold Stress Model, without porous jumps, but when I set the porous jumps and set the constant values for it and run calculation after 50 iteration solver become diverged. :confused: What I am doing wrong?
what do you mean porous jump?
I worked on a cyclone with RSM turbulence model. It's somehow difficult to get a good converged solution, but don't know anything about porous jump? Why is it used for? Maybe you need to start with a simpler turbulence model such as k-e then, after a few iterations go to RSM. Even, you need to start an unsteady simulation. Anyway, I'll be glad to hear about porous jump. thank you

 recepky March 6, 2013 06:11

Porous jump is a boundry condution that can be used for any adjacent walls, porous jump is 1D solution equvalent of 3D porous zone.

 oj.bulmer March 6, 2013 08:17

Are you sure you have put the right permeability and C2 values for porous jump? Also, any specific reason for RSM model?

I have so far observed that Realizable model works best with the porous jumps, amongst all other 2-equation turbulence models. Perhaps, if you really want RSM, you can start with realizable model, have a decent convergence, and then switch to RSM.

OJ

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