modify a intern variable of Fluent with scheme and UDF

fanch33 · February 27, 2015, 10:25

Hi everybody,

I want to modify at each time step in each cell, the constant Cepsilon2 (Ceps2) from the k-epsilon RANS model that we can access from the viscous model panel.
In my UDF, I compute the value I want for Ceps2 in a C_UDMI variable.

From what I read, I think that I need to send this value from the UDF to a scheme program (using RP_Set_Real) to update the value of Ceps2.

How can I get back the value with a scheme program ?

Thanks for your help

Fanch

maverick123 · March 2, 2015, 02:32

Hi Fanch,

As per my understanding, you have to use DEFINE_ADJUST routine, not rp_vars.

Best Regards

Kokemoor · March 2, 2015, 10:54

The turbulent model constants are actually already stored as Scheme variables, so you shouldn't need to write any Scheme code. The constant C2-Epsilon for the RNG model is stored in the variable rng-kec2. If you use RP_Set_Real("rng-kec2",Ceps2) in your DEFINE_ADJUST macro, I don't think you'll need to do anything else.

fanch33 · March 2, 2015, 11:01

thank you for your answer Kokemoor.

I thought that I needed to use a scheme because my company give me a manual on that, but a bit obsolete...

But you're right, I tried RP_Set_Real in my UDF this morning and the Ceps2 value were updated as I wanted.

Anyway, thanks for your answer

February 27, 2015, 10:25	modify a intern variable of Fluent with scheme and UDF	#1
fanch33 Member Join Date: Feb 2015 Posts: 32 Rep Power: 11	Hi everybody, I want to modify at each time step in each cell, the constant Cepsilon2 (Ceps2) from the k-epsilon RANS model that we can access from the viscous model panel. In my UDF, I compute the value I want for Ceps2 in a C_UDMI variable. From what I read, I think that I need to send this value from the UDF to a scheme program (using RP_Set_Real) to update the value of Ceps2. How can I get back the value with a scheme program ? Thanks for your help Fanch

March 2, 2015, 10:54		#3
Kokemoor Senior Member Andrew Kokemoor Join Date: Aug 2013 Posts: 122 Rep Power: 13	The turbulent model constants are actually already stored as Scheme variables, so you shouldn't need to write any Scheme code. The constant C2-Epsilon for the RNG model is stored in the variable rng-kec2. If you use RP_Set_Real("rng-kec2",Ceps2) in your DEFINE_ADJUST macro, I don't think you'll need to do anything else. ingpeppe likes this.

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March 2, 2015, 02:32		#2
maverick123 Member Join Date: Nov 2014 Posts: 31 Rep Power: 11	Hi Fanch, As per my understanding, you have to use DEFINE_ADJUST routine, not rp_vars. Best Regards

March 2, 2015, 11:01		#4
fanch33 Member Join Date: Feb 2015 Posts: 32 Rep Power: 11	thank you for your answer Kokemoor. I thought that I needed to use a scheme because my company give me a manual on that, but a bit obsolete... But you're right, I tried RP_Set_Real in my UDF this morning and the Ceps2 value were updated as I wanted. Anyway, thanks for your answer