[ck5285]

Hi All Users
Would like to understand if anyone has performance benchmark studied between CFX vs Flow-3D? especially focus on VOF and moving meshing options. Thanks in advance

[ghorrocks]

Hi,

I have done a simple comparison so have some comments. Flow3D can't do moving mesh per-se, it does it by having a fixed background mesh and sweeps the bodies over it. This approach is much simpler than the moving mesh approach of CFX, but the full moving mesh approach means you can have a more tailored grid with wall refinement and other refinements. If accurate boundary layer resolution is important that will be tricky in Flow3D.

Flow3D has many VOF technologies CFX does not have. The single fluid VOF model in Flow3D is fantastic if it is appropriate to your model. It will run much faster than CFX's multiphase VOF model (like 100 times faster in some applications) but I had problems getting it to give me sensible droplet shapes when surface tension was activated.

If you are doing lots of VOF then I definitely recommend you look at Flow3D. But on the other hand I found Flow3D's interface to be poor compared to CFX, and CFX has many features Flow3D does not have (CEL, extensive scripting, advanced multiphase/chemistry).

Which is best depends on what you want to do. They both have strengths and weaknesses.

Glenn Horrocks

[ck5285]

Hi Glenn Horrocks
Thanks for your details reply, but which Flow-3D & CFX version that you did benchmark last time? and under which application? Thanks

[ck5285]

Hi Glenn Horrokcs
Btw can you share the comparison results with me? any web link available?

[ghorrocks]

Hi,

I have used CFX from version 3 (!) up to the beta version of V12 and everything in between. I have used it for over 10 years. The Flow3D version was 9.3, we trialled it a few months back. I have not used Flow3D before except during this trial.

The application is commercial and I am not at liberty to disclose details. So no, you can't see the results and definitely no web pages. I will say it is simulating inkjet printers but I cannot give any more detail than that.

Glenn Horrocks

[ck5285]

Hi
I believe you are the expert in CFX. So for inkjet droplets simulation which CFD program predicted most accurate result compared to actual data? Thanks again.

[ghorrocks]

Which was more accurate? Neither. We currently use Fluent! Don't forget accuracy is only one consideration... cost, ease of use, software stability, physics relevant to your intended model, quality of support, ability to scale to large simulations etc etc also are important.

Glenn Horrocks

[ck5285]

So is that means Fluent are the best among CFX & Flow-3D in this droplet VOF simulation?

[ghorrocks]

Hi,

What is your application?

Glenn

[ck5285]

similar to Inkjet simulation, where the droplets is generated through VOF and need to travel/move along a path during the droplets generation. so what is your comments?

[ghorrocks]

Hi,

You already have my comments - I recommend you try Fluent and/or Flow3D.

Glenn Horrocks

[ck5285]

I may not have luxury to try both, so based on your experience which one (Fluent vs Flow-3D) provided better accuracy and shorter simulation time? Thanks again.

[ghorrocks]

Hi,

I would have to know more about what you are trying to do to give a recommendation!

Glenn Horrocks

[ck5285]

Hi
pls advice what additional information is needed? Thanks

[yong]

Hi,
I have been using ansys cfd and flow3d. For comparisons, I would give higher grade for Ansys in graphical presentation. However, I would still prefer flow3d for its multi-physics capability to simulate great models.

[ckleanth]

Originally Posted by ck5285

Hi
pls advice what additional information is needed? Thanks

ring Ansys and Flow3D sales team, give them a problem description and request them to benchmark their software against your problem. If you are to buy a license from either of them it shouldn't be a problem.

[feizaghaee]

Originally Posted by ghorrocks

Hi,

I have done a simple comparison so have some comments. Flow3D can't do moving mesh per-se, it does it by having a fixed background mesh and sweeps the bodies over it. This approach is much simpler than the moving mesh approach of CFX, but the full moving mesh approach means you can have a more tailored grid with wall refinement and other refinements. If accurate boundary layer resolution is important that will be tricky in Flow3D.

Flow3D has many VOF technologies CFX does not have. The single fluid VOF model in Flow3D is fantastic if it is appropriate to your model. It will run much faster than CFX's multiphase VOF model (like 100 times faster in some applications) but I had problems getting it to give me sensible droplet shapes when surface tension was activated.

If you are doing lots of VOF then I definitely recommend you look at Flow3D. But on the other hand I found Flow3D's interface to be poor compared to CFX, and CFX has many features Flow3D does not have (CEL, extensive scripting, advanced multiphase/chemistry).

Which is best depends on what you want to do. They both have strengths and weaknesses.

Glenn Horrocks

i'm modeling an open channel flow by CFX. but after 5 months i haven't had any sensible result yet. CFX cann't simulate secondary currents correctly and consequently max velocity location. i need to use Reynolds stress models to simulate those currents. you said that Flow-3D is more powerful than CFX in free sufrace but flow-3D dosen't have Reynodls stress model. which software is more powerful in simulating Reynolds stress?

[ghorrocks]

Your question states the answer - if you need RSM models then you need a solver which supports RSM models and that counts Flow3D out and leaves you with CFX.

[zandi]

Originally Posted by ghorrocks

Flow3D has many VOF technologies CFX does not have. The single fluid VOF model in Flow3D is fantastic if it is appropriate to your model. It will run much faster than CFX's multiphase VOF model (like 100 times faster in some applications) but I had problems getting it to give me sensible droplet shapes when surface tension was activated.

If you are doing lots of VOF then I definitely recommend you look at Flow3D. But on the other hand I found Flow3D's interface to be poor compared to CFX, and CFX has many features Flow3D does not have (CEL, extensive scripting, advanced multiphase/chemistry).

Hi
thanks for your advices
in another post about VOF in CFX you have mentioned that:

"There is nothing "wrong" with the free surface modelling in CFX, it is just that it does not capture the interface as sharply as some other approaches. Whether this is a problem or not depends on the application. CFX has been successfully used on many free surface applications"

is it right to say that CFX is weak in specifying the free surface place?
I have to read the documentations but would yu help me with the method that CFX use for free surface?
be cause the Eulerian Eulerian method in multiphase modeling is not recomended for multiphase systems that researches would be done about finding the interface of two phases
thank you

[ghorrocks]

is it right to say that CFX is weak in specifying the free surface place?

CFX is used by many people to do very demanding free surface simulations. So no, it is not weak.

help me with the method that CFX use for free surface?

Do the tutorials, listen to your fluid mechanics lecturer, go to CFX training and read the literature. That's what I did and it will work for you.