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-   -   density update by UDF in non-premixed combustion (http://www.cfd-online.com/Forums/fluent/30531-density-update-udf-non-premixed-combustion.html)

IKSOO November 18, 2002 11:49

density update by UDF in non-premixed combustion
 
Dear all,

I am currently using FLUENT 6 under linux.

I am trying to find what DEFINE_**** can update my own UDF of density in non-premixed combusiton model.

In the material pannal, I can not change the density... the manual says.. density is only a function of temperature.. but the updated density is not.

Could you tell me how to feedback the new density field to FLUENT combusiton model ?

( the new density can take the calculated values from FLUENT, such as velocities, turbulent energy, species, mixture fraction and variances.... etc.)

many thanks

mahdi saniee nezhad November 24, 2002 01:59

Re: density update by UDF in non-premixed combusti
 
Dear sir I have a problem with this title. If it's possible for you please send me your received responses. Very thanks for your attention to my request. With the best regards. Mahdi saniee nezhad


J.W.Ryu December 8, 2002 21:37

Re: density update by UDF in non-premixed combusti
 
I am not sure this is correct way or not. If you can make out file for density of domain where you are willing to know, you can put it on your UDF for density.

UDF for density (of course, should be interpreted type) Macro : automatic iteration with initialization Out file : density data calculated by each iteration External program : check Out file and exchange density of your UDF, and run Macro.

In my case, of couser I do not consider density, I made above four different file types to optimize calulation, especially temeprature at specific point.

External program starts Macro --> run Fluent with initial condition after initialization --> when converged, External file checks "out" file(in my case, temperature of specific point) --> calculate new input at external program (recalculate input power based on temperature of "out" file) --> exchange new input value in Macro or UDF --> run again Macro

Sequential iteration gave me final well converged results from 2~3 repeated iteration.

Probably, you may need to use this kinds of method.

I hope this is helpful to your trouble.

Thanks,

J.W.Ryu


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