[paoching]

I'm looking at a galvanic corrosion damage problem using fluent electric potential model and are writing a udf with DEFINE_GRID_MOTION to update the dynamic damage of metal surface. The equation looks like this:

corr_rate = (J*MWT)/(z*F*RHO)
y(1)=y(0)+corr_rate*dt

where
corr_rate is surface damage in m/s
J is electric current magnitude in A/m^2, a post processing variable
MWT is molecular weight of metal in g/mol
z is charge number of dissolved metal ion
F is Faraday's constant in C/mol
RHO is density of metal in g/m^3

problem is I don't know how to pass electric current J into the UDF. I've looked through the UDF manual and while I can call cell variable like pressure and temperature with C_P(c,t) and C_T(c,t), there is no similar macro for electric current.

Can someone help me?

Thanks in advance!

[paoching]

A little update, I was able to deform mesh with hard entered constant current density J. see attached UDF, which is hooked to dynamic mesh zone.
my problem lies in how and if I can pass the post processing variable current density into UDF.
2018-07-17_12-15-20.png

2018-07-17_12-14-20.png

corrosion_al.c

[Domagoj]

Hello, did you managed to pass electric current J into the UDF?
How did You do it?

Thanks!

[paoching]

Originally Posted by Domagoj

Hello, did you managed to pass electric current J into the UDF?
How did You do it?

Thanks!

I was able to pass the potential gradient from fluent to the UDF and calculate current density with ohms law

[Domagoj]

Originally Posted by paoching

I was able to pass the potential gradient from fluent to the UDF and calculate current density with ohms law

Thanks, did You use C_PHI_1(c,ct) and C_PHI_G(c,ct)[i] cell macros?
I am not sure because this macro is not in documentation.

Best regards.

[ghc]

Originally Posted by Domagoj

Thanks, did You use C_PHI_1(c,ct) and C_PHI_G(c,ct)[i] cell macros?
I am not sure because this macro is not in documentation.

Best regards.

Hi,

Has anyone used those commands succesfully? I am stucked with SIGSEGV errors while trying to obtain the electric potential gradient...

Best regards

[AlexanderZ]

Originally Posted by ghc

Hi,

Has anyone used those commands succesfully? I am stucked with SIGSEGV errors while trying to obtain the electric potential gradient...

Best regards

i recommend you to open new thread and explain in details your problem
describe case, model you are using, show code and compilation log

list of avaliable macros for specific models you may find in

..\fluent\fluent_xxx\addons\model_name\src