CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   CFX (http://www.cfd-online.com/Forums/cfx/)
-   -   Convergence + view Condensation (http://www.cfd-online.com/Forums/cfx/120498-convergence-view-condensation.html)

martijnal July 8, 2013 11:00

Convergence + view Condensation
 
Hi,
I tried to find a tutorial with someting familiair to my model but I could not find it.

I'm modelling a spray condenser: Hot gasses (T=500C, 50% N2, 50% hydrocarbon vapour A) enter at the bottom. I set this fluid as my continious fluid.

A spray of droplets (10C, 100% hydrocarbon B, 0% hydrocarbon A) is used to cool the fluid and condense hydrocarbon A.

What I cannot get working is a converged solution: the solver line keeps oscilating.
What I already tried:
Larger time scale factor
Mesh refinement
No gas flow/ no spray (conclusion: spray is the one that causes the lack of convergence)

1.Can anyone give me some advice on how to let the simulation converge?

2. When looking at the post processing, I cannot find a variable that shows how much of the hydrocarbon A is condensed and through what outlet it is flowing. I can see the massfraction of the vapour of A but not the liquid component. How can I view this?

I put my ccl file online: https://www.dropbox.com/s/ydx1n8bynzmhih1/condenser.ccl

ghorrocks July 13, 2013 07:44

Have you seen the FAQ on this? http://www.cfd-online.com/Wiki/Ansys...gence_criteria

Finer meshes are more likely to have convergence problems than coarser meshes. This is due to the reduced dissipation in finer meshes. So you might have more luck on convergence on coarse meshes, but of course accuracy may suffer.

Are you using turbulent dispersion on the particle tracks? The documentation explains that obtaining convergence can be very difficult with this option activated.


All times are GMT -4. The time now is 18:15.