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 vega August 22, 2005 02:17

KIVA-conserved scalar

Dear all,

I am facing a problem related with coupling of PDF-conserved scalar algorithm with KIVA code. I do hope any of you could help me by giving some hints.

Dealing with diffusion flame, I have succesfully implemented the transport equations of mean and variance of mixture fraction into KIVA. Consequently, a beta-function PDF of mixture fraction can also be obtained. Based on this PDF, I could also obtain the mean reactive scalars (species concentration, density, temperature, and enthalpy). Until this point, I did well.

However, in order to obtain the correct flow field, for the flow equation in KIVA I have to use the mean density obtained by PDF approach. So I specified the mean density in KIVA with the value I obtained using PDF, and I also deactivated subroutine ysolve (to calculate the species mass fraction) since I think this task is also taken over by PDF.

The problem is, when I tried to execute the code, temperature overflow occured. And after checking the code, I found that this temperature overflow is related with subroutine state, where the state equation is solved. And subroutine state is related with subroutine tsolve, where mean temperature is solved based on energy equation (original KIVA scheme), not by PDF integration.

So my questions would be:

1. Which subroutines do I have to disregard when dealing with pdf method in KIVA?

2. In this case, do I still need iteration (known as big iteration in KIVA) to calculate the flow field? As far as I can understand, given that I have the mean density obtained by pdf, I just have to use this mean density in subroutine vsolve (where velocity field is solved) and deactivate tsolve, psolve, and state. In addition, the temperature is defined by the mean temperature I obtained by PDF integration. Is this correct?

3. Do you have any suggestion on this problem?

Thank you very much for your kind help.

cheers,

vega

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