# Mixing of air and CO2

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August 24, 2011, 16:36
Mixing of air and CO2
#1
New Member

Tobias
Join Date: Aug 2011
Posts: 5
Rep Power: 8
Hi, I have no experience with CFX Pre. So I hope someone can help me. I would like to calculate the mixing of CO2 after a nozzle with air. In the sketch you can see the construction.

I have 2 meshes. One for die nozzle and one for the pipe. Therefore there is a interface at the end of the nozzle (red marked).

Now my question: What I have to set in CFX Pre for both domains? In the domain of the lance I have set "CO2 ideal gas" (calorically perfect ideal gas) as material. I think that's right. But what should I set in the other domain? Is it enough to set "ideal gas" as material. Or do I consider CO2 as material?

Can someone tell me the correct settings, please? Thank you!
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 August 24, 2011, 18:46 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 14,199 Rep Power: 109 No need for multiple domains. Just use a single domain. Use a multicomponent gas if you want to fully model the mixing process, but you could simplify this model down to a single component (ie air) and add the CO2 as an additional variable if you like. This is much simpler, but does not take into account the full fluid property changes due to mixture composition. Whether these fluid property changes are significant enough to mean a multicomponent mixture model is required is up to you.

 August 25, 2011, 03:09 #3 New Member   Tobias Join Date: Aug 2011 Posts: 5 Rep Power: 8 Now I have the following settings: 1 domain for both meshes in Fluid and Particle Definitions: Ideal Air Gas und CO2 Ideal Gas as Continuous Fluid Turbulence model for both fluids is SST At the nozzle inlet I have set the Bulk Mass Flow Rate and Volume Fraction of CO2 is 1 and of Ideal Air is 0. At the pipe inlet I have set the Bulk Mass Flow Rate and Volume Fraction of CO2 is 0 and of Ideal Air is 1. Is that ok?

 August 25, 2011, 18:45 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 14,199 Rep Power: 109 Sounds sensible.

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