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-   -   udf problem (http://www.cfd-online.com/Forums/fluent/33402-udf-problem.html)

kanazawa April 5, 2004 18:31

udf problem
 
i inquire the posibility of modeling doxin emission using fluent.

kanazawa April 6, 2004 05:11

Re: udf problem
 
my meaning is that it is impossible to simulate other gas pollution emission (mercury)by fluent soft

Ale April 6, 2004 06:05

Re: udf problem
 
You should be able to simulate almost any pollutant emission, provided you have defined the required UDS and written a proper UDF with all the chemical and physical models you need to describe the formation of the particular pollutant you are interested in (I didn't understand if you are interested in mercury or dioxines).

What kind of problems are you encountering?

Regards,

Ale

kanazawa April 6, 2004 06:16

Re: udf problem
 
Dear Ale: thank you for your information, i want to simulate the distribution of mercury during sludge combustion, i used fluent soft two years ago, however, i do not sure i can simulate the distribution of mercury by soft.if i have the code, i can finish the project.hence, i inquire the possibility, if it can simulate the distribution, then i will do. of course, i have model of formation gas mercury.

bestregard

han

kanazawa April 6, 2004 06:24

Re: udf problem
 
Dear Ale: i find UDS is only mass flow, how to add other uds? this is my problem.

best regard

han

Ale April 6, 2004 08:46

Re: udf problem
 
Han,

I think that you can do what you'd like, but It does not mean that it will be easy. It can take some time to learn writing UDF, debug, solve numerical problems and modelling issues, and so on...

User Defined Scalars can be any scalar (concentration, molar or mass fraction, enthalpy...) with any unit. Mass flow rate is just the flux function that is used to solve the scalars' transport equations (this means that you should multiply by the fluid density the source terms for the scalars).

I think that it would be good for you to go through the UDF manual to learn UDF features and capability, to understand what kind of effort you will need and to see if you can afford it.

Best regards,

Ale

kanazawa April 6, 2004 21:25

Re: udf problem
 
Dear Ale: After i browse the udf manual, i did not find how to add the concentration scalar in fluent. In fact, i solve this problem in china by fortan code and wrote some code about the formation and transformation of gas mercury. however, i have not the copyright of fortran code , hence i can not use the fortran code in japan, the professor in japan suggest that i use fluent soft to solve the problem. hence, i inquire you if it is possibility of finishing the work using fluent soft. if it is impossible, i would not waste my time.

Though i get some information about this problem, i did not find how do add the user define scalar in fluent soft, can you give me more information?At the same time, i write to officer of fluent corporation .

best regard

han

Ale April 7, 2004 04:38

Re: udf problem
 
Hi, Again: I think that it is possible to do what you would like to do, and I ask other posters to confirm or deny what I am saying.

Read more carefully the UDF User's Guide. You'll find in chapter 9 all you can need to know on User Defined Scalars Transport Modelling.

You have to define the number of scalars you need (e.g. 1 scalar = 1 species concentration), and solve the corresponding transport equations. You'll never find how to add 'species concentration'...Fluent only sees scalars, no matter of what they are, it will be your care to make calculations consistent. You can define the source terms for each scalar by the macro DEFINE_SOURCE. You can use DEFINE_ADJUST to perform any calculation you need to repeat before each iteration. You should refer to the UG for further information and details.

It will need some effort to learn everything you need...so, If you ask me whether it is possible to solve the problem, I would answer yes; if you ask me whether you'll solve the problem in few days or even in few weeks, I would answer maybe not.

Good luck,

Ale

kanazawa April 7, 2004 20:33

Re: udf problem
 
Dear Ale: After discuss with you and other people, i know how to finish this work and i will try my best to finish this project in several months.thank you for your help.

bestregard

han


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