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-   -   Fluent 6.3 32bit vs Fluent 12.0 64bit (http://www.cfd-online.com/Forums/fluent/69344-fluent-6-3-32bit-vs-fluent-12-0-64bit.html)

ibex7 October 20, 2009 07:11

Fluent 6.3 32bit vs Fluent 12.0 64bit
 
Hi all. I'm in need of help.badly. Recently, I did some simulations of MAV using Fluent 12 and what I really interested in was lift coefficient, CL and drag coefficient, CD. But to my dismay, the fluent 12 gave very small value of CL, in magnitude of -7x10^-3 and CD was around 2x10^-1. My supervisor was unhappy with the value of CL and I used fluent 6.3 to see if there was any differences. At the end of iteration of fluent 6.3, the value of CL is far more closer than what my supervisor had expected. So, my question is, does these 2 versions of Fluent give significant difference in results? Could some one please tell me which version is really useful in giving accurate results? Both simulation used the same source of case file. Now, I begin to suspect that fluent 12 64bit gives more accurate results because I'm using 64bit Windows 7 Ultimate. Native application meets the native OS. Fluent 6.3 was used on my PC as comparison. My PC specs: Intel C2D 1.8GHz Windows 7 64Bit Ultimate Edition 7GB of RAM

Philipov October 20, 2009 08:17

Try to install the two versions on one and the same OS... After that you can conclude. In fact... Fluent is not a "system" code, so it is expected to give equal results.... Try to find the different options in the two versions ... some default values may be added that are not present in the 6.3.26...

-mAx- October 20, 2009 09:00

*comparison of residuals
*comparison of pressure distribution
*comparison of velocity distribution
*comparison of other quantities
*serial/parallel computing? (watch out you may not call a case file from an x computation, and load the data file from an y computation --> typical: case pre-processing on serial, switch to parallel... run, and save ONLY data from parallel... After a read case AND data, you get weird results for sure)

in other word, it is debugging! (and it also belongs to CFD)
But you shouldn't have huge difference between 2 computations. On the other hand (as Philipv mentionned), you shouldn't have exactly the same result

ibex7 October 20, 2009 09:21

Quote:

Originally Posted by Philipov (Post 233376)
Try to install the two versions on one and the same OS... After that you can conclude. In fact... Fluent is not a "system" code, so it is expected to give equal results.... Try to find the different options in the two versions ... some default values may be added that are not present in the 6.3.26...

Fluent 6.3.26 32bit was installed together with fluent 12 64bit on Windows 7 64bit Ultimate. I'm on the middle of investigating further the differences.

ibex7 October 26, 2009 04:21

Quote:

Originally Posted by -mAx- (Post 233379)
*comparison of residuals
*comparison of pressure distribution
*comparison of velocity distribution
*comparison of other quantities
*serial/parallel computing? (watch out you may not call a case file from an x computation, and load the data file from an y computation --> typical: case pre-processing on serial, switch to parallel... run, and save ONLY data from parallel... After a read case AND data, you get weird results for sure)

in other word, it is debugging! (and it also belongs to CFD)
But you shouldn't have huge difference between 2 computations. On the other hand (as Philipv mentionned), you shouldn't have exactly the same result

FYI, both fluent 6.3.26 n fluent 12.0 were set to hv 1*10^-6 in residuals, both gave almost similar pressure n velocity distribution, and it was setup to run in serial. on both version, case and data file were recalled from the same angle of attack.

Now, I'm running the simulation in parallel using fluent 12.0 since fluent 6.3.26 can't be setup for parallel processing on my personal pc.

-mAx- October 26, 2009 04:29

Get the force on the body (where you get your Cd & Cl), you will have the force from pressure and viscosity.
Compare your results, and you will see where is the difference (pressure or viscosity).
If results are the same, then your problem is on the reference values

DarrenC October 30, 2009 02:53

Hi ibex7,

Did you have any problems setting up fluent parallel, or it was just a case of using default settings when running parallel? I am having a problem running fluent parallel atm. I have a new i7 running windows 7 home premuim. It just keeps hanging everytime it tries to create a new process. Serial works fine though. Any thoughts?

wlt_1985 April 18, 2011 02:44

Quote:

Originally Posted by ibex7 (Post 233367)
Hi all. I'm in need of help.badly. Recently, I did some simulations of MAV using Fluent 12 and what I really interested in was lift coefficient, CL and drag coefficient, CD. But to my dismay, the fluent 12 gave very small value of CL, in magnitude of -7x10^-3 and CD was around 2x10^-1. My supervisor was unhappy with the value of CL and I used fluent 6.3 to see if there was any differences. At the end of iteration of fluent 6.3, the value of CL is far more closer than what my supervisor had expected. So, my question is, does these 2 versions of Fluent give significant difference in results? Could some one please tell me which version is really useful in giving accurate results? Both simulation used the same source of case file. Now, I begin to suspect that fluent 12 64bit gives more accurate results because I'm using 64bit Windows 7 Ultimate. Native application meets the native OS. Fluent 6.3 was used on my PC as comparison. My PC specs: Intel C2D 1.8GHz Windows 7 64Bit Ultimate Edition 7GB of RAM

Quote:

Originally Posted by DarrenC (Post 234583)
Hi ibex7,

Did you have any problems setting up fluent parallel, or it was just a case of using default settings when running parallel? I am having a problem running fluent parallel atm. I have a new i7 running windows 7 home premuim. It just keeps hanging everytime it tries to create a new process. Serial works fine though. Any thoughts?


Dear All,

I am working with window 7 professional 64 bit operating system. While installing Fluent version 6.3.26 (64 bit), message appears as below:

This installation does not support window operating system.....(seem like do have compatibility issue)

Were you all facing this problem before? How you guys solve it? Any suggestion to me?

Thanks for help.

Best regards


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