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siddhukb June 17, 2010 07:18

cyclone separator multiphase help
1 Attachment(s)
I am trying to model cyclone separator in CFX. Based on the previous help from this forum i modeled both air and aluminium particles as continuous medium. the solution converged after 1000 iteration.

Now i am trying to model air as continuous medium and aluminium as particle transport solid. i have used uniform particle distribution with min and max dia as 1micron and 100 micron respectively.For turbulence i have used SSG reynolds stress model. I have used point cone for particle injection. The solution is not getting converged and it is oscillating.

I have attached the ccl file.
I really need some help

Thank you
Attachment 3806

ghorrocks June 17, 2010 08:17

Reynolds stress turbulence models are always hard to converge. I seem to remember telling you this before - only use a RSM model if you really need it and for a particle transport model I doubt you need it.

Here are some tips:

siddhukb June 17, 2010 08:25

I choose SSG be cause it gave the better solution when both air and aluminium were continuous fluid
I am going to try with Shear stress model. Is this model ok for particle transport model?


ghorrocks June 17, 2010 19:38

As I said previously, if you are adding the complexity of a particle transport model then the last thing you need is making convergence even more difficult by using a RSM model. The extra "accuracy" you get from a RSM model will probably be lost in the multiphase behaviour anyway so there is little point. So SST is a much better choice. Only go to RSM if you can clearly show that SST is inadequate.

siddhukb June 17, 2010 23:47

I tried with SST. The solver ran for 1000 iterations. The solution is not converged. It is still oscillating. And the domain imbalances are huge. Really need some help.


ghorrocks June 17, 2010 23:50

Have you tried the tips on the cfd-online wiki page?

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