Different Results from Fluent 5.5 and Fluent 6.0
 

Hi everybody,

I had been using Fluent 5.5 regularly since last one year. Most of the time I was simulating turbulent flow in a tundish with one inlet and six outlets. Using Fluent 5.5 after getting the steady state k-e model results I used to switch to unsteady state species transport model for tracer dispersion study. Whenever I used fluent 5.5 I got reasonable results in my RTD analysis. Recently we upgraded to Fluent 6.0. So when I ran the same case files of species transport model I am getting highly erroneous results.

I haven't changed anything. Simply ran the case again using Fluent 6.0.

Thanks in advance

Rajeev

Could anyone throw some light what could be the mistake or is it a BUG in Fluent 6.0.

Results from Fluent 5.5 had been validated through actual experimental results so I don't think its results are wrong.

Re: Different Results from Fluent 5.5 and Fluent 6
 

Dear Rajeev,

I'm afraid I cannot help you with your problem regarding Fluent 5 and 6, but I am interested because I have been using the species model in Fluent 5 for 6 months now. I have been set the task of using the species model to model the movement of dye through a small pipeline. However, I have not been able to match up the results exactly (approximately 30% difference if the parameter of interest). How did you compare your Fluent and experimental results and have you published any results on the web or in journals?

Thanks in advance John

Re: Different Results from Fluent 5.5 and Fluent 6
 

Hi Rajeev,

I've experienced the same problem, in my case Fluent 6.0 changed all kind of settings like turning off gravity.

Good luck.

Re: Different Results from Fluent 5.5 and Fluent 6
 

Do you have radiation (DO) model activated? I have found a problem there. Talk to your Fluent support asap.

regars,

LW

Re: Different Results from Fluent 5.5 and Fluent 6
 

This is interesting - I'm also having some problems with Fluent 6 - in particular with the journal files - it seems to randomly give me the error:

Error: undefined read macro Error Object: ()

while executiong my journal commands. I can't trace any particular problem with the commands, Fluent just chucks a wobbly rather randomly.

Anyone had this problem?

Perhaps we're really beta testing the new code. It makes you wonder a bit about how good these codes really are, doesn't it.

Perhaps if you're happy with the results from Fluent 5.5, you should stick to that!

Greg

Re: Different Results from Fluent 5.5 and Fluent 6
 

Fortunately I cannot report anything about differences in results between fluent 5.5 und 6.0 but what I obserevd are non-working new (small) features like xy-plot for pathlines (supposed to be fixed with 6.0.20), flexible time step, animation in the solving menue, ...

Hard problems occured with non-conformal interfaces which could be defined with fluent 5.5 and not with fluent 6 (lately fluent support provided a scheme command which helped.);

parallel jobs: I have a case with periodic-boundaries which cannot be run in parallel mode (after hours no it) with fluent 6 but without problems with fluent 5.5.

Maybe you observed similar problems?? Maybe it is just the coincidence of the new version aix5.1 and fluent6.0? Who knows?

hi
 

Hi Rajeev,
This is Srinivas. I have started modelling tundish flow using Fluent6.2
Can you please help me out in starting the problem? I want you to share any material regarding tutorials on this topic.

Thanks in advance.