[amin.z]

hey friends

I have a question about turbulent of multiphase flows!
I'm modeling a bubbly flow and I'm using Eulerian multiphase!
the problem is about turbulent modeling!
In interaction tab, there is a tab as "Turbulent Dispersion" and we have these 3 choices:
1.none
2. Lopez de Bertodano
3. Simonin
4. Burns et al
5. Diffusion in vof
6. UDF

in your idea which model is better for my problem?

Thanks in advance!

[amin.z]

Any idea?
for which model, each of them is appropriate?

[P_VS]

Hello!
I just have the same doubt. What did you finally choose?

[amin.z]

Hi,

It was a long time ago, but here is what I found:

1. According to my personal communications with Dr. Bertodano, his model is very old and the coefficient of the model is completely arbitrary. He recommended me to use other available models.

2. According to my personal communications with Dr. Burns, his model could be taken advantage for low Stokes number flows, which is almost always the case for bubbly flow, in view of their small relaxation time scale. The Simonin model should also be applicable, and should give virtually the same results as FAD in this limit. The FAD model is less applicable for high Stokes number flows, for example large solid particles and drops, for which the Simonin model would be better.

Unfortunately I didn't find any reliable references about the rest of the models.

[P_VS]

Thank you very much!
As you say, It is not easy to find references about this.

I really appreciate your help

[Mel B]

Hi! Options include -none- for turbulence dispersion force.
What does this mean if we select -none- option?

[minzhang]

1. Low Stokes number flows, I am wondering how low is low? 0.1 is low?

2. The Simonin model is applicable for both low and high Stokes number?

3. What is FAD here?

Thanks!

Originally Posted by amin.z

Hi,

It was a long time ago, but here is what I found:

1. According to my personal communications with Dr. Bertodano, his model is very old and the coefficient of the model is completely arbitrary. He recommended me to use other available models.

2. According to my personal communications with Dr. Burns, his model could be taken advantage for low Stokes number flows, which is almost always the case for bubbly flow, in view of their small relaxation time scale. The Simonin model should also be applicable, and should give virtually the same results as FAD in this limit. The FAD model is less applicable for high Stokes number flows, for example large solid particles and drops, for which the Simonin model would be better.

Unfortunately I didn't find any reliable references about the rest of the models.

[minzhang]

I am wondering whether you have an answer now?
Thanks!

Originally Posted by Mel B

Hi! Options include -none- for turbulence dispersion force.
What does this mean if we select -none- option?

[vinerm]

To get answers to these questions, it is better to go through their relevant articles.

None is just none; no model applied, i.e., no turbulent dispersion included. It's user choice, of course. Low Stokes number means lower than even 0.1, usually an order of magnitude lesser but even 0.1 can be considered low. FAD means Favre Averaged Drag model, based on Burns et al. work.

A. D. B. Burns, et al. The Favre Averaged Drag Model for Turbulent Dispersion in Eulerian Multi-Phase Flows

O. Simonin and P. L. Viollet. Modeling of Turbulent Two-Phase Jets Loaded with Discrete Particles

J. O. Hinze. Turbulence

[geth03]

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