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-   -   secondary phase velocity with ASMM ???? (http://www.cfd-online.com/Forums/fluent/29059-secondary-phase-velocity-asmm.html)

 fawzy November 8, 2001 12:07

secondary phase velocity with ASMM ????

I m using the algebraic slip mixture model in stirred tank and i want to use the secondary phase cell velocity in some UDF. How can i access to its name (argument)

 Isa November 12, 2001 06:42

Re: secondary phase velocity with ASMM ????

Hi!

You didn't answer my querstion before on the dispersed phase volume fraction.

I know you said that you are using ASMM, but my question was relating to validity of the use of ASM. To be able to use ASm with any accuracy at all, your solids (disperse) VF will have to be very low (< 1%).

What is the physical disperse VF of solids that you have?

 fawzy November 12, 2001 13:28

Re: secondary phase velocity with ASMM ????

Hi Isa i have answerd you last week see "multiphase in fluent 5.5" my answer was :

"I don't use dispersed solid phase. I use the ASMM for gas sparging in mixed tank. So it is no limitation for the gas volume fraction as gas density << primary fluid density. See always "On mixture model for multiphase flow", Manninen & Taivassalo, VTT energy, VTT publications 288. available via the web in pdf format (67 pages).

Have you any idea about my question ? thanks

thanks

 Isa November 19, 2001 05:43

Re: secondary phase velocity with ASMM ????

Hi!

And my question was:

'I know you said that you are using ASMM, but my question was relating to validity of the use of ASM. To be able to use ASm with any accuracy at all, your solids (disperse) VF will have to be very low (< 1%)'

There is no point in answering your question about ASM if it is not an appropriate model to use.

There's no point in using a model just because its easier. If it is known, that the model is inappropriate (i.e. will give completely the wrong answer as it doesn't incorporate half the physics), then why are you doing the modelling?

Therefore, I ask again, what is the physical volume fraction of the solids?

 fawzy November 19, 2001 12:40

Re: ASMM

I dont 't use solid but gas as dispersed phase. I don't use dispersed solid phase. I use the ASMM for gas sparging in mixed tank. So it is no limitation for the gas volume fraction as gas density << primary fluid density. I know that when density of primary phase is smaller than the secondary phase density ASMM is only applicable for low volume fraction (less than 10% ) and size of solid less than 50 um.

It s not the case in my problem where i use water as continuous phase ans air as secondary phase

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