# Cyclone with Lots of Porous Jumps = Divergence

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 March 3, 2013, 04:26 Cyclone with Lots of Porous Jumps = Divergence #1 New Member   Recep Kaya Join Date: Feb 2013 Posts: 6 Rep Power: 6 Sponsored Links 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. What I am doing wrong?

March 4, 2013, 15:09
#2
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A-A Azarafza
Join Date: Jan 2013
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Quote:
 Originally Posted by recepky 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. 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

 March 6, 2013, 06:11 #3 New Member   Recep Kaya Join Date: Feb 2013 Posts: 6 Rep Power: 6 Porous jump is a boundry condution that can be used for any adjacent walls, porous jump is 1D solution equvalent of 3D porous zone.

 March 6, 2013, 08:17 #4 Senior Member   OJ Join Date: Apr 2012 Location: United Kindom Posts: 475 Rep Power: 13 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 A CFD free user likes this.

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