problem with two fluid domains

s.amirzadeh · November 17, 2014, 00:09

Hi,im trying to analysis a model with two separated fluid domains,there is a solid domain between fluid domains,the problem is that i want to set one domain material water and the other one air,but when i change material for one domain,other one changes and they become same as each other.
some tips would be helpful.

ghorrocks · November 17, 2014, 04:10

If you use the default CFX options you have to model this as a multiphase model. A bit silly, isn't it?

To get around this there is an expert parameter which allows you to have different fluids in different domains. I cannot remember the name of it, do a search of the forum (or CFX documentation) to find it.

Opaque · November 17, 2014, 10:28

This topic has been discussed at length in this forum.

Edit CFX-Pre options, enable beta features and disable constant physics.

NOTE: once you disable constant physics (which enforces same fluid settings for all fluid domains), you must be very careful the physics setup is consistent. The software basically removes several safeguards (reason it is still beta).

Hope the above helps,

Martin_Sz · November 19, 2014, 04:09

define mixture as fluid material n2 o2 co2 and h2o . then on the separated domains set fractions of these materials

evcelica · November 19, 2014, 09:50

Opaque's way it the best way to do it.

November 17, 2014, 00:09	problem with two fluid domains	#1
s.amirzadeh New Member Join Date: Oct 2014 Posts: 23 Rep Power: 11	Hi,im trying to analysis a model with two separated fluid domains,there is a solid domain between fluid domains,the problem is that i want to set one domain material water and the other one air,but when i change material for one domain,other one changes and they become same as each other. some tips would be helpful.

November 17, 2014, 04:10		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144	If you use the default CFX options you have to model this as a multiphase model. A bit silly, isn't it? To get around this there is an expert parameter which allows you to have different fluids in different domains. I cannot remember the name of it, do a search of the forum (or CFX documentation) to find it. s.amirzadeh likes this.

November 17, 2014, 10:28		#3
Opaque Senior Member Join Date: Jun 2009 Posts: 1,852 Rep Power: 33	This topic has been discussed at length in this forum. Edit CFX-Pre options, enable beta features and disable constant physics. NOTE: once you disable constant physics (which enforces same fluid settings for all fluid domains), you must be very careful the physics setup is consistent. The software basically removes several safeguards (reason it is still beta). Hope the above helps, s.amirzadeh likes this.

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November 19, 2014, 04:09		#4
Martin_Sz Senior Member Marcin Join Date: May 2014 Location: Poland, Swiebodzin Posts: 313 Rep Power: 13	define mixture as fluid material n2 o2 co2 and h2o . then on the separated domains set fractions of these materials

November 19, 2014, 09:50		#5
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,176 Rep Power: 23	Opaque's way it the best way to do it.