Learning Forum

[Mike H.]

Hello,

Background: I have a large chemical reaction mechanism running in 2D Fluent. It consists of 24 reactions and 17 species. I am looking to do sensitivity studies, where I turn off a reaction, then re-run to get its contribution to the results.

I previously tried deactiviting specific reactions in the mechanism be de-selecting them. However, for reasons unknown, that did not actually deactivate them. A sure way to deactivate is to set the pre-exponential factor to a small fraction of its original value, say, two orders of magniutude lower. This effectively turns off the reaction.

Now to the issue. Doing this with the GUI is painful, so I am doing it with scheme commands. 

Problem: The (rpsetvar 'materials mymaterials) does not actually update the materials database or the GUI. 

Possible Solution: By searching through this document [https://www.cfdyna.com/CFDHT/SchemeLanguage.pdf], I found a command called set-all-materials!. This one actually works and updates the GUI values.

Question: Does anyone know why rpsetvar doesn't work? Also, does an easier way to update kinetic parameters exist (non-GUI)?

Thanks.

BTW, here is my workflow:

(define mat (%rpgetvar 'materials))

(define mymaterials (replace mat 1.5e+14 1.5e+12))

(set-all-materials! mymaterials)

where "replace" is a scheme procedure I found online:

(define (replace lst find repl)
    (if (pair? lst)
        (cons
            (replace (car lst) find repl)
            (replace (cdr lst) find repl))
        (if (equal? find lst)
            repl
            lst)))

[SVV]

Hi,

To change the Arrhenius coefficients without GUI, one way is to transcribe reactions into a Chemkin mechanism and then use a recorded journal to read another version of the mechanism.

 

Please note, as per part of forum policy, we cannot debug/write scripts.

 

[Mike H.]

v.v.,

Thank you for the suggestion, and I appreciate that scripts can break Fluent if not careful! I am doing some other work in Chemkin, so I will look into that. 

Can I import multiple Chemkin mechanisms and then switch between them in cell zones?  Or, do I overwrite the mechanism each time I import. 

Thank you.