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-   -   multiphase VS multicomponet (http://www.cfd-online.com/Forums/cfx/19039-multiphase-vs-multicomponet.html)

Fread July 2, 2002 02:47

multiphase VS multicomponet
 
dear all

anybody know what is multiphase same or difference from multicomponet?

Bart Prast July 2, 2002 04:49

Re: multiphase VS multicomponet
 
multiphase example: water vapour + liquid water multicomponent example: air(oxygen, nitrogen, carbondioxide, etc)

Fread July 3, 2002 00:35

Re: multiphase VS multicomponet
 
Thank you Bart Prast for you answer and i have some quation ..

If mywork have water(liquid)+air can i use multicomponent (water+O2+N2+CO2)? Or I must use multiphase only.

Hwan Shin July 3, 2002 01:03

Re: multiphase VS multicomponet
 
Multi-component flow: The species are mixed at the molecular level. The model equations solve for common velocity and temperature fields, and mass transfer of one species in another is governed by diffusion driven by concentration gradients.

Multi-phase flow: The species are mixed at much larger than molecular length scale. They are given potentially different velocity and temperature fields etc., and these interact via empirically specified inter-phase transfer terms.

from CFX4 user manual

Fread July 3, 2002 04:19

Re: multiphase VS multicomponet
 
Thank you Hwan Shin for your answer.

Bouke July 3, 2002 09:39

Re: multiphase VS multicomponet
 
I don't think you can use multicomponent fluids in multiphase simulations in CFX 5.5 (but please correct me if I'm wrong).

In multicomponent fluids the density is a function of composition, temperature and pressure. Hence multicomponent fluids are always compressible and you cannot do compressible multiphase simulations in CFX 5.5.

However, it might be possiible in the upcoming version: "CFX-5.5.1 can now simulate low speed compressible multiphase problems." (from the CFX website).

Whether you need to use a multicomponent fluid is another question, only if there is some significant (for the flow) change in composition in your model. If the composition change does not influence the flow then you might consider using additional scalars instead of components.

good luck,

Bouke


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