Error Message after switching to multi domain physics

chili023 · June 4, 2010, 07:22

Hello everybody,
I am simulationg a shocktube in cfx with two domains that are connected by an interface (one with exhaust gas one with air). I simulated the whole case with constant domain physics. It worked fine. Now i realized that I can disable constannt domain physics
After unchecking the constant domain physics, I get the following message
error in PEEKI
CDANAM= MOM_FLO2 / IEQN

Does anybody know why I get this error after switching to multi physics????

THX

ghorrocks · June 4, 2010, 09:18

Disabling constant domain physics only works if the domains are not connected, such as two domain separated by a solid region. If the two domains have an interface it will not work, so no surprises it gave an error.

If you have multiple working fluids then you need a multicomponent simulation, and no need for disabling constant domain physics.

chili023 · June 4, 2010, 10:09

Ohh Ok. thx.
Could u please tell me how u would do this.
I want two interconnected domains with different gas properties (one 293K 2bar Air/ and one 873K 2bar Exhaust gas(CO2/N2/H20)). My goal is to sent a pressurewave through the domains.
I want to see the change of amplitude and change of speed of the wave. The percentage of mixing between the two gases would be a nice bonus.
My problem is that ansys thinks that both gases are mixed, ( I can tell because the cp and Ideal gas consatnt are constant over x (both domains) and an average out of the two gas cp's)

What should I do.

ghorrocks · June 5, 2010, 06:28

I think there is a CO2/air tutorial with CFX, have a look at that one. That will show you how to set up multicomponent mixtures.

June 4, 2010, 07:22	Error Message after switching to multi domain physics	#1
chili023 New Member AB Join Date: Jun 2010 Posts: 21 Rep Power: 16	Hello everybody, I am simulationg a shocktube in cfx with two domains that are connected by an interface (one with exhaust gas one with air). I simulated the whole case with constant domain physics. It worked fine. Now i realized that I can disable constannt domain physics After unchecking the constant domain physics, I get the following message error in PEEKI CDANAM= MOM_FLO2 / IEQN Does anybody know why I get this error after switching to multi physics???? THX

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June 4, 2010, 09:18		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,844 Rep Power: 144	Disabling constant domain physics only works if the domains are not connected, such as two domain separated by a solid region. If the two domains have an interface it will not work, so no surprises it gave an error. If you have multiple working fluids then you need a multicomponent simulation, and no need for disabling constant domain physics.

June 4, 2010, 10:09		#3
chili023 New Member AB Join Date: Jun 2010 Posts: 21 Rep Power: 16	Ohh Ok. thx. Could u please tell me how u would do this. I want two interconnected domains with different gas properties (one 293K 2bar Air/ and one 873K 2bar Exhaust gas(CO2/N2/H20)). My goal is to sent a pressurewave through the domains. I want to see the change of amplitude and change of speed of the wave. The percentage of mixing between the two gases would be a nice bonus. My problem is that ansys thinks that both gases are mixed, ( I can tell because the cp and Ideal gas consatnt are constant over x (both domains) and an average out of the two gas cp's) What should I do.

June 5, 2010, 06:28		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,844 Rep Power: 144	I think there is a CO2/air tutorial with CFX, have a look at that one. That will show you how to set up multicomponent mixtures.