Using user function variables in expressions

jlamb · July 6, 2023, 08:24

Hi,

I am trying to model a stent in a blood vessel as a type of porous media. To do this, instead of a 3D porous domain, I am attempting to use a 2D interface with a pressure change as defined in the theory documentation. This seems simple enough with constant Kloss and Kperm coefficients but my aim is to have them vary over the stent to represent a heterogenous interface.

As far as I can work out, this should be doable with User Functions and Expressions. Essentially, I have imported spatial data with a Kloss and Kperm variable as an interpolation function (which appear on the right place of my mesh), and have tried to include them in an expression for the pressure change dP.

Unfortuantely, I cannot get this to work I get the error message 'Bad expression value 'dP' detetcted in parameter 'Pressure Change' in object '/FLOW:Flow Analysis 1/DOMAIN INTERFACE:STENT/INTERFACE MODELS/MASS AND MOMENTUM/MOMENTUM INTERFACE MODEL'. CEL error: The following unrecognised names were referenced: Kloss.Kloss, Kperm.Kperm.

It feels like their should be a simple fix but I can't for the life of me figure out, any help would be much appreciated.

ghorrocks · July 6, 2023, 19:42

It says it is just a CEL error, which means you syntax is wrong. Please attach your CCL or output file.

July 6, 2023, 08:24	Using user function variables in expressions	#1
jlamb New Member Join Date: Jul 2023 Posts: 3 Rep Power: 2	Hi, I am trying to model a stent in a blood vessel as a type of porous media. To do this, instead of a 3D porous domain, I am attempting to use a 2D interface with a pressure change as defined in the theory documentation. This seems simple enough with constant Kloss and Kperm coefficients but my aim is to have them vary over the stent to represent a heterogenous interface. As far as I can work out, this should be doable with User Functions and Expressions. Essentially, I have imported spatial data with a Kloss and Kperm variable as an interpolation function (which appear on the right place of my mesh), and have tried to include them in an expression for the pressure change dP. Unfortuantely, I cannot get this to work I get the error message 'Bad expression value 'dP' detetcted in parameter 'Pressure Change' in object '/FLOW:Flow Analysis 1/DOMAIN INTERFACE:STENT/INTERFACE MODELS/MASS AND MOMENTUM/MOMENTUM INTERFACE MODEL'. CEL error: The following unrecognised names were referenced: Kloss.Kloss, Kperm.Kperm. It feels like their should be a simple fix but I can't for the life of me figure out, any help would be much appreciated.

July 6, 2023, 19:42		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	It says it is just a CEL error, which means you syntax is wrong. Please attach your CCL or output file. Opaque likes this. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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