cfd or cfx

marry · October 1, 2009, 06:45

Dear All,

I am quite a new user, I will be working on multiphase flows. Can you please tell me which is better, CFD or CFX for working on these sort of modellings. thanks in advance.

marry

zebG · October 1, 2009, 08:42

CFX is simply the name of the Ansys CFD code.

Thus CFX = a type of CFD

marry · October 1, 2009, 09:15

sorry, for confusing. What I meant was that I see some papers used fluent for multiphase flow modelling. thats why I am asking if fluent or cfx better for multiphase flow modelling??

zebG · October 4, 2009, 10:36

I've not used Fluent, so you'd have to wait on the advice of others. I'd suggest you change the title of the thread first though.

Bak_Flow · October 5, 2009, 09:34

Hi marry,
CFX and Fluent each have their advantages. If you have access to both codes that is good and you can try things out yourself and report back to us.

IMHO CFX has more robust solver technology. In general the equation sets are solved coupled in CFX. As you add additional physics like turbulence equations, species, volume fractions, etc...they could be solved coupled or segregated. Some time ago (I think version 11) CFX added coupled volume fractions as well as segregated. Although coupled was not the default yet (because coupling everything together sometimes makes the problem too stiff) it usually converges much faster than segregated volume fractions. So it works well!

Fluent, in general solves everything segregated. For multi-phase I believe they added some full coupling options but I was never able to get it to work....and the time/iteration was much much higher than segregated.....maybe I did not try enough!

In terms of models CFX has some nice models built in but (again IMHO) really hard to add anything fancy because you often have to go to use user Fortran.

Fluent is much better to add models with UDF's as you will find there are oodles of things people have done out there...check publications, conferences, university courses, etc.

Support is now the same since both are under Ansys.

Tell us more about the specifics of the problems you are doing and maybe we can help more?

Regards.........Bak_Flow

marry · October 6, 2009, 03:48

Dear Bak_Flow,

Thank you very much for your reply.
I have only fluent 6.1 and dont have cfx. To be honest I am very new and at the moment I am doing the tutorials that I have found from the books and the internet. I did some experimental work on gas/liquid two phase flow. Therefore eventually I intend to model these sort of flows, coalescence, break-up etc of drops and bubbles.
Since I was quite at the beginning and I have a goal at the end, I wanted to know if I should start from directly to cfx or fluent.

What should be my steps in order for me to step into the multiphase flow studies, would it be possible for you to tell me??

I appreciate your messages

marry

marry · October 6, 2009, 03:49

thank you ZebG,

I have changed it

October 1, 2009, 06:45	cfd or cfx	#1
marry New Member marry Join Date: Sep 2009 Posts: 8 Rep Power: 16	Dear All, I am quite a new user, I will be working on multiphase flows. Can you please tell me which is better, CFD or CFX for working on these sort of modellings. thanks in advance. marry

October 1, 2009, 09:15	fluent or cfx	#3
marry New Member marry Join Date: Sep 2009 Posts: 8 Rep Power: 16	sorry, for confusing. What I meant was that I see some papers used fluent for multiphase flow modelling. thats why I am asking if fluent or cfx better for multiphase flow modelling??

October 6, 2009, 03:48	fluent or cfx for multiphase flows	#6
marry New Member marry Join Date: Sep 2009 Posts: 8 Rep Power: 16	Dear Bak_Flow, Thank you very much for your reply. I have only fluent 6.1 and dont have cfx. To be honest I am very new and at the moment I am doing the tutorials that I have found from the books and the internet. I did some experimental work on gas/liquid two phase flow. Therefore eventually I intend to model these sort of flows, coalescence, break-up etc of drops and bubbles. Since I was quite at the beginning and I have a goal at the end, I wanted to know if I should start from directly to cfx or fluent. What should be my steps in order for me to step into the multiphase flow studies, would it be possible for you to tell me?? I appreciate your messages marry

October 6, 2009, 03:49	fluent or cfx for multiphase flows	#7
marry New Member marry Join Date: Sep 2009 Posts: 8 Rep Power: 16	thank you ZebG, I have changed it

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October 1, 2009, 08:42		#2
zebG New Member RobT Join Date: Aug 2009 Posts: 9 Rep Power: 16	CFX is simply the name of the Ansys CFD code. Thus CFX = a type of CFD

October 4, 2009, 10:36		#4
zebG New Member RobT Join Date: Aug 2009 Posts: 9 Rep Power: 16	I've not used Fluent, so you'd have to wait on the advice of others. I'd suggest you change the title of the thread first though.

October 5, 2009, 09:34		#5
Bak_Flow New Member Join Date: Jun 2009 Posts: 8 Rep Power: 16	Hi marry, CFX and Fluent each have their advantages. If you have access to both codes that is good and you can try things out yourself and report back to us. IMHO CFX has more robust solver technology. In general the equation sets are solved coupled in CFX. As you add additional physics like turbulence equations, species, volume fractions, etc...they could be solved coupled or segregated. Some time ago (I think version 11) CFX added coupled volume fractions as well as segregated. Although coupled was not the default yet (because coupling everything together sometimes makes the problem too stiff) it usually converges much faster than segregated volume fractions. So it works well! Fluent, in general solves everything segregated. For multi-phase I believe they added some full coupling options but I was never able to get it to work....and the time/iteration was much much higher than segregated.....maybe I did not try enough! In terms of models CFX has some nice models built in but (again IMHO) really hard to add anything fancy because you often have to go to use user Fortran. Fluent is much better to add models with UDF's as you will find there are oodles of things people have done out there...check publications, conferences, university courses, etc. Support is now the same since both are under Ansys. Tell us more about the specifics of the problems you are doing and maybe we can help more? Regards.........Bak_Flow