# Problem with writing UDF-EDDY DISSIPATION MODEL

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 August 8, 2017, 05:39 Problem with writing UDF-EDDY DISSIPATION MODEL #1 Member   Join Date: Apr 2017 Location: india Posts: 96 Rep Power: 7 I am working on a eddy dissipation model for the combustion of a fuel with mixture of species(CH4, CO, H2, H20, C2H6, CO2, N2, O2) in air. I am trying to attach a CO source term as a concentration sink and this source term has the dependence on only the mass fraction of CO not on other species from the combustor to the sink. For calculation of CO concentration i am going to use (C_YI (c,t,i)*vol of sink region) where this source term will be attached, this i index for all species in the mixture I want to know how to get the value of 'i' (index) of CO

 August 11, 2017, 09:37 #2 Senior Member   Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0 if in your simulation settings you have the following list of species, in this order: CH4 CO H2 H2O then i=0 for CH4, i=1 for CO, i=2 for H2, i=3 for H2O. It depends on the order the species are listed in the mixture definition.

 August 14, 2017, 02:14 #3 Member   Join Date: Apr 2017 Location: india Posts: 96 Rep Power: 7 Thanks a lot for ur reply and time sir. I have two species mass fraction to find out as mentioned in the code , according to what you have mentioned sir i should give i1=3 for co2 and i2=6 for co and give it directly in the id_co and id_co2 section below rt sir MF1=C_YI(c,t,id_co); MF2=C_YI(c,t,id_co2); but when i give it "parse error" is coming Last edited by sooraj546; September 7, 2017 at 08:44.

August 16, 2017, 02:38
Problem in retrieving value from a boundary
#4
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Join Date: Apr 2017
Location: india
Posts: 96
Rep Power: 7
Hello, I'm new on this forum. I use fluent and i have some problems.
problem def:
there 2 main parts a combustor and a sink as shown in the fig below . In the combustor region a mixture of gases(ch4,co,o2,co2,h2,c2h6,n2,h20) are going in through fuel inlet and air is supplied through the air inlet COMBUSTION happens inside the combustor and temperature, mass fraction etc can be found out inside the combustor.

now i want to add source term of temperature co and co2 to the sink and for eg for source term calculation the temperature from the boundary between the sink and the combustor should go into the UDF code. i am specifying the UDF AGAIN. kINDLY PLZ HELP ME OUT I AM TOTALLY STUCK
Attached Images
 forum fig.jpg (106.5 KB, 6 views)

Last edited by sooraj546; September 7, 2017 at 08:44.

 August 16, 2017, 02:59 #5 Member   Join Date: Apr 2017 Location: india Posts: 96 Rep Power: 7 sir , i have incorporated this in my code , still few new doubts are there kindly help me out sir