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Old   February 14, 2006, 11:16
Default case files UDF volumetric reaction rate
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Good Morning,

I am working on chemical reaction (graphite oxidation and CO combustion at aproximately 800 C ) in FLUENT. I need to build a UDF because the reaction rates don't follow at all the Arrhenius law. However, I have never programmed in C before. I would apreciate very much if someone could send me examples of UDF for Define_sr_rate or Define_vr_rate. Any comment on how the UDF actually modifies the rate first computed using the Arrhenius model would be more than welcome.

Thanks, Marie-Anne
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Old   February 20, 2006, 02:33
Default Re: case files UDF volumetric reaction rate
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In fluent, chemical reactions particulary the combustion reactions are modelled by: 1. Arrehnius law: for reaction kinetic controlled reactions 2. Eddy Dissipation Model: for gaseous reactions controlled by turbulence mixing

Therefore, it has got one algorithm called EDC, eddy dissipation concept where it calculates reactions from both the models and take the minimum of both the values.

** more UDF on reaction rates ...... go to fluent documentation and then UDF section .... u will get some standard UDFs, which u can copy and then modify cells, threads etc according your problem to hook-up it.

Plz do write whether it helped you or not ?
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Old   February 24, 2006, 10:43
Default Re: case files UDF volumetric reaction rate
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Hey Kumar,

Sorry for not answering sooner, but I was out of office. Thank you for your answer. My problem is more that I don't really know how to program, but I am trying to use exemples from the UDF manual. I am having right now a floating point error message. If you have any idea where that might come from...


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