There's several good packages out there that can deal with these types of flow. Consider the exact demands that you have, as well as your budget, and make your decision based on that. There is no general "best".   I've only worked with ANSYS, from what I noticed (and hear from other users), FLUENT is best in terms of speed, CFX wins in stability. Both are rather complete in terms of models, but as FLUENT originates from aerodynamics, it seems to be broader in turbulence modeling, where CFX stems more from the field of rotary equipment. COMSOL is newer in fluids, but has a strong multi-physics background. From what I heard from colleagues, the Siemens packages (Star-CCM etc.) are very good at numerics (stability and so), but have less choice in models. Anyway, all packages will have the basic functionalities required for multi-phase flow modeling. It may be that your specific application requires a specific type of inter-phase closure models or turbulence models which are not generally available, so that may be one thing to look for in your personal best match. And then of course there's the open source packages such as OpenFoam. Steeper learning curve, but it can save you a lot of money, especially if you're not in academia. 

Dear Alireza, usual commercial package like Fluent, CFX or Comsol Multiphysics have modules for multi-phase flow simulations; but also there are some specific softwares, usually managed by Universities Depts or Research Labs, which can be very useful for your aimes.  Gianluca

Dear Dr Argentini

Do you know some of these codes, can I find on the web?

Thank you very much

Regards.

There's several good packages out there that can deal with these types of flow. Consider the exact demands that you have, as well as your budget, and make your decision based on that. There is no general "best".   I've only worked with ANSYS, from what I noticed (and hear from other users), FLUENT is best in terms of speed, CFX wins in stability. Both are rather complete in terms of models, but as FLUENT originates from aerodynamics, it seems to be broader in turbulence modeling, where CFX stems more from the field of rotary equipment. COMSOL is newer in fluids, but has a strong multi-physics background. From what I heard from colleagues, the Siemens packages (Star-CCM etc.) are very good at numerics (stability and so), but have less choice in models. Anyway, all packages will have the basic functionalities required for multi-phase flow modeling. It may be that your specific application requires a specific type of inter-phase closure models or turbulence models which are not generally available, so that may be one thing to look for in your personal best match. And then of course there's the open source packages such as OpenFoam. Steeper learning curve, but it can save you a lot of money, especially if you're not in academia. 

Dear Cees

Thank you very much for your detailed considerations. I need a software for simulation of the injection of air to the free-surface flow. I simulated it with flow-3D soft. While it couldn't indicate the entrance of bubbles in free surface flow, nor volume fraction of void in free-surf.

Regards.

Do remember that the injection of single bubbles is an extremely computationally intensive thing to simulate. In any case, you will probably need to resort to euler-euler models which do not track individual bubbles, but only averaged gas fractions. Probably you will need to monitor mass for volume flux through a surface plane, and via the average bubble size, retrieve bubble number from that. All above packages should be able to do so. (and I would expect flow-3D to be capable of that too, it has multiphase capacities)

Dear Cees 

Thank you so much for your great guidance. I simulated this problem by One-Fluid and void fraction computation physics in Flow-3D, its results not good enough, while this soft can simulate two-fluid ( as two-phase flow) and I didn't do it yet. Maybe it gives accurate results.

Regards.

I THINK ANSYS FLUENT IS GOOD COMMERCIAL CFD SOFTWARE

REGARDS

Dear Alireza, see e.g. the following links.  Gianluca

http://www.ida.upmc.fr/~zaleski/paris/index.html

https://mfix.netl.doe.gov/mfix/

Dear Dr Gianluca Argentini

I am so grateful of you. These models are so great.

Thanks a lot.

Regads.

Dear Alireza,

I am currently using ANSYS fluent ver. 17.2 commercial code for simulating multi-phase flow system (fluidised beds, bubble column). I think it's better in terms of computational time.

Dear Md. 

Thank you veey much for your useful guidance.

Regards.

From their performance analysis,It is  observed that, the commercial codes fail to converge and produce accurate results, and leave much to be desired with respect to direct numerical simulation of flows with free interfaces. The academic software code on the other hand was shown to be computationally efficient, produced very accurate results, and outperformed the commercial codes by a magnitude or more.