Problem with CEL syntax for additional variable

rbezerra · July 30, 2015, 14:47

Dear all,

I'm trying to model the heat generation caused by reaction through an additional variable. This worked fine on a single liquid phase model. When going to a multiphase (liquid + air), I obtain the following error message in the subdomain tab.

error1.jpg

When I try to rename the additional variable to Resin.alpha (Resin being the fluid name), it does not accept the syntax, I get the following error:

error2.PNG

It seems the dot is not being accepted, but on several CFX help pages, there are several examples of CEL expressions where <Fluid.> is the usual syntax for a fluid prefix.

Anyone would have any idea what I'm doing wrong?

Thanks in advance,

Renato

Opaque · July 30, 2015, 15:48

The first image is missing.

However, for multiphase flow simulations it is sometimes required to use the full name of the variable. For example, MyFluid.MyAdditionalVar.

It does not mean that the variable is defined as MyFluid.MyAdditionalVar, but you want to access the MyAdditionalVar associated to MyFluid. You only have to defined the additional variable as MyAdditionalVar, and activate it on the fluid of interest.

Hope the above helps,

rbezerra · July 31, 2015, 04:18

Thanks for the reply Opaque!

I could fix it by defining just the expressions like you said.
Now I get error messages for the interfaces between the region I'm applying the additional variable to (a porous domain) and a solid domain surrounding it.

"The object "ADDITIONAL VARIABLE: alpha" is present in the object... but it is not physically valid."

However, I cannot disable this option at the refered interface setup.

interface_setup.PNG

Any hint on that?

Opaque · July 31, 2015, 11:33

I am sorry.. Difficult to tell w/o more context.

Definitely, the software indicates the Additional Variable is not allowed on such interface for some reason.

Is the additional variable active for all phases in the domains on both sides of the interface ?

rbezerra · July 31, 2015, 11:47

Hi Opaque,

The additional variable is now active just for the fluid (and not for air), and just for the porous domain, i.e. I created a subdomain for the extra variable which is located only in the porous domain.

The geometry is exactly the same as in the single phase case, but there I didn't have any error message regarding these interfaces porous-solid. The error appeared only after switching to multiphase.

July 30, 2015, 14:47	Problem with CEL syntax for additional variable	#1
rbezerra New Member Join Date: Jan 2015 Posts: 6 Rep Power: 11	Dear all, I'm trying to model the heat generation caused by reaction through an additional variable. This worked fine on a single liquid phase model. When going to a multiphase (liquid + air), I obtain the following error message in the subdomain tab. error1.jpg When I try to rename the additional variable to Resin.alpha (Resin being the fluid name), it does not accept the syntax, I get the following error: error2.PNG It seems the dot is not being accepted, but on several CFX help pages, there are several examples of CEL expressions where <Fluid.> is the usual syntax for a fluid prefix. Anyone would have any idea what I'm doing wrong? Thanks in advance, Renato Last edited by rbezerra; July 30, 2015 at 14:54. Reason: Picture didn't show

July 30, 2015, 15:48		#2
Opaque Senior Member Join Date: Jun 2009 Posts: 1,880 Rep Power: 33	The first image is missing. However, for multiphase flow simulations it is sometimes required to use the full name of the variable. For example, MyFluid.MyAdditionalVar. It does not mean that the variable is defined as MyFluid.MyAdditionalVar, but you want to access the MyAdditionalVar associated to MyFluid. You only have to defined the additional variable as MyAdditionalVar, and activate it on the fluid of interest. Hope the above helps, lordluan likes this.

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July 31, 2015, 04:18		#3
rbezerra New Member Join Date: Jan 2015 Posts: 6 Rep Power: 11	Thanks for the reply Opaque! I could fix it by defining just the expressions like you said. Now I get error messages for the interfaces between the region I'm applying the additional variable to (a porous domain) and a solid domain surrounding it. "The object "ADDITIONAL VARIABLE: alpha" is present in the object... but it is not physically valid." However, I cannot disable this option at the refered interface setup. interface_setup.PNG Any hint on that?

July 31, 2015, 11:33		#4
Opaque Senior Member Join Date: Jun 2009 Posts: 1,880 Rep Power: 33	I am sorry.. Difficult to tell w/o more context. Definitely, the software indicates the Additional Variable is not allowed on such interface for some reason. Is the additional variable active for all phases in the domains on both sides of the interface ?

July 31, 2015, 11:47		#5
rbezerra New Member Join Date: Jan 2015 Posts: 6 Rep Power: 11	Hi Opaque, The additional variable is now active just for the fluid (and not for air), and just for the porous domain, i.e. I created a subdomain for the extra variable which is located only in the porous domain. The geometry is exactly the same as in the single phase case, but there I didn't have any error message regarding these interfaces porous-solid. The error appeared only after switching to multiphase.