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-   -   Problem with Non-Premixed model (coal burner) (http://www.cfd-online.com/Forums/fluent/44917-problem-non-premixed-model-coal-burner.html)

Nando June 4, 2007 10:44

Problem with Non-Premixed model (coal burner)
 
Hello:

Im modeling a coal burner with non-premixed model. Ive got one fuel stream (coal) and two oxidizer stream with different compositions.

I must apply two-mixture-fraction approach.(three stream with different composition).DPM iteraction every 25 continuous phase iteraction.

Ive a problem about this approach:

Fluent update properties continuous phase every ten iterations. I plot some variables (temperature,O2,mass flow rate).

When Fluent do this update properties, these variables increase or decrease its value too much (example: Tempearture changes from 2000 K to 500 K approximately, it changes from 500 to 2000 at the next update it happens every 10 iterations).

The solution cant converge because of these great changes of the fluid properties.I dont understand this approach.

Could somebody explain me two mixture fraction approach?

How can i converge my case?

My english is so bad.Im sorry.

Thanks


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