Hi Can anybody tell me the major difference between the Mixture and the Eulerian multiphase models in Fluent? Thanks. Shankar.

Here are the limitations of the two models. In my case, the lack of energy equation required to use mixture model.

Mixture limitations :

You must use the segregated solver. The mixture model is not available with either of the coupled solvers.

Only one of the phases can be compressible.

Streamwise periodic flow (either specified mass flow rate or specified pressure drop) cannot be modeled when the mixture model is used.

Species mixing and reacting flow cannot be modeled when the mixture model is used.

Solidification and melting cannot be modeled in conjunction with the mixture model.

The LES turbulence model cannot be used with the mixture model.

The second-order implicit time-stepping formulation cannot be used with the mixture model.

The mixture model cannot be used for inviscid flows.

The shell conduction model for walls cannot be used with the mixture model.

Eulerian model limitation

Only the k- models can be used for turbulence.

Particle tracking (using the Lagrangian dispersed phase model) interacts only with the primary phase.

Streamwise periodic flow (either specified mass flow rate or specified pressure drop) cannot be modeled when the Eulerian model is used.

Compressible flow is not allowed.

Inviscid flow is not allowed.

The second-order implicit time-stepping formulation cannot be used with the Eulerian model.

Melting and solidification are not allowed.

Species transport and reactions are not allowed.

Heat transfer cannot be modeled.

The only type of mass transfer between phases that is allowed is cavitation; evaporation, condensation, etc. are not allowed.

Hi Thanks for your response which shows the limitations of both the models.But what is the major difference between these two models.Thanks. Shankar.

The major difference between the mixture model and the Eulerian multiphase models is that for the mixture model you solve ONE momentum equation for the n-phases being transported while for the Eulerian multiphase models you solve N momentum equations for the n-phases.

Addressing the interaction between phases is also different. In the mixture model, this is modelled through an algebraic relationship...quite simple. In the Eulerian multiphase models, the interaction is addressed by incorporating source terms, which contain a drag function. The drag function is typically empirical.

Thanks for your reponse.

[heng03313]

Hi, could anyone shed light as to why Eulerian multiphase cannot have compressible flow?

[SJSW]

2003
http://jullio.pe.kr/fluent6.1/help/html/ug/node733.htm
It's not allowed to use compressible flow with Eulerian model.
Inviscid flow is not allowed as well.

2006
https://www.sharcnet.ca/Software/Flu...ug/node950.htm
You can define only one compressible fluid phase.
Another compressible fluid phase could be achieved by UDF.
Inviscid flow is still not allowed.

However, I can't succeed simulating the bubble injected from a mass inlet at the bottom of a half-filled tank using ANSYS14. The bubble is phase-2 and compressible.
It seems that some tricks should be adopted.
Could someone kindly help, please?