Additional variable in multiphase flow

Raijin Thunderkeg · January 14, 2014, 04:17

Hi, every1.

Now i have a problem about the additional variable in a two-phase flow. In CFX-pre, an additional variable has been set to Fluid Dependent on the Fluid Models tab. And transport equation is selected for one fluid on Fluid Specific Models tab. This equation is solved in the whole domain. But i just want it to be solved in the fulid specific region. How to do this? Can you give me some suggestions?

Thanks.

ghorrocks · January 14, 2014, 04:48

But isn't the phase which has the AV present everywhere in the domain, even if it is just about zero in some places?

Raijin Thunderkeg · January 14, 2014, 07:09

Thanks for your reply. Once i did a simulation on the mixing process in a water-air system using AV. When i display the contour of AV in CFD-Post, it presents everywhere. It is very strange because the tracer is just a species of water and the AV belongs to the water. Now i know i may have some misunderstanding here. What should i do to correct this? Multiply AV by a volume fraction?

ghorrocks · January 14, 2014, 16:58

Yes, to limit to one phase for post processing you could generate a new variable which is the AV * volume fraction.

January 14, 2014, 04:17	Additional variable in multiphase flow	#1
Raijin Thunderkeg Member JESS Join Date: Nov 2010 Posts: 31 Rep Power: 15	Hi, every1. Now i have a problem about the additional variable in a two-phase flow. In CFX-pre, an additional variable has been set to Fluid Dependent on the Fluid Models tab. And transport equation is selected for one fluid on Fluid Specific Models tab. This equation is solved in the whole domain. But i just want it to be solved in the fulid specific region. How to do this? Can you give me some suggestions? Thanks.

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January 14, 2014, 04:48		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	But isn't the phase which has the AV present everywhere in the domain, even if it is just about zero in some places?

January 14, 2014, 07:09		#3
Raijin Thunderkeg Member JESS Join Date: Nov 2010 Posts: 31 Rep Power: 15	Thanks for your reply. Once i did a simulation on the mixing process in a water-air system using AV. When i display the contour of AV in CFD-Post, it presents everywhere. It is very strange because the tracer is just a species of water and the AV belongs to the water. Now i know i may have some misunderstanding here. What should i do to correct this? Multiply AV by a volume fraction?

January 14, 2014, 16:58		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Yes, to limit to one phase for post processing you could generate a new variable which is the AV * volume fraction.