How to set the different Ref. Density in fluid domains?

M29 · November 8, 2019, 08:52

hi all,

I want to set air and helium in two fluid domains respectively.

Two fluid domains are separated by solid domain.

But in cfx, in fluid domain, the fluid set automatically same.

So, I found two method.

a. Use "Enable Beta Features"
b. Use Multi-component mixture

The method "a" is unstable that i know, so i will use method "b".

Q1) How can i set the properties about multi component mixture? Is it okay to just use "ideal mixture" option in transport, radiation(and so on..) properites?

Q2) My case is in natural convection. So I want to set full buoyancy model in two fluid domains. How can i set the Ref. density? Use average density about air and He? or Is there a method to insert different Ref. density respectively?

I will anticipate your answer... thank u.

Opaque · November 8, 2019, 09:51

May I ask what is the problem with "Enable Beta Features"?

Did you untoggle the Constant Domain Physics?

M29 · November 12, 2019, 03:10

Quote:

Originally Posted by Opaque

May I ask what is the problem with "Enable Beta Features"?

Did you untoggle the Constant Domain Physics?

Sorry, I'm late...

first, I don't know exactly about function of that. Just I know that if i use the enable beta features, different fluids can set in two fluid domains respectively. But I heard that is unstable. So i didn't use that.

second, actually i use the Constant domain physics in cfx - option - general.

ghorrocks · November 12, 2019, 05:15

Enabling beta features means you are using features which are not fully tested, so could be inaccurate, unstable or misleading. They are recommended for advanced users who can spot when the solver is doing silly things. But used correctly they allow many extra features to be available. So it's your call about whether you use them or not.

November 8, 2019, 08:52	How to set the different Ref. Density in fluid domains?	#1
M29 New Member Sumin Park Join Date: Jul 2019 Posts: 26 Rep Power: 7	hi all, I want to set air and helium in two fluid domains respectively. Two fluid domains are separated by solid domain. But in cfx, in fluid domain, the fluid set automatically same. So, I found two method. a. Use "Enable Beta Features" b. Use Multi-component mixture The method "a" is unstable that i know, so i will use method "b". Q1) How can i set the properties about multi component mixture? Is it okay to just use "ideal mixture" option in transport, radiation(and so on..) properites? Q2) My case is in natural convection. So I want to set full buoyancy model in two fluid domains. How can i set the Ref. density? Use average density about air and He? or Is there a method to insert different Ref. density respectively? I will anticipate your answer... thank u.

November 12, 2019, 05:15		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Enabling beta features means you are using features which are not fully tested, so could be inaccurate, unstable or misleading. They are recommended for advanced users who can spot when the solver is doing silly things. But used correctly they allow many extra features to be available. So it's your call about whether you use them or not. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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November 8, 2019, 09:51		#2
Opaque Senior Member Join Date: Jun 2009 Posts: 1,880 Rep Power: 33	May I ask what is the problem with "Enable Beta Features"? Did you untoggle the Constant Domain Physics?