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-   -   A bout difference between CFX and CFD-Fatran (http://www.cfd-online.com/Forums/cfx/21031-bout-difference-between-cfx-cfd-fatran.html)

w0er February 26, 2005 15:58

A bout difference between CFX and CFD-Fatran
 
I have used the same grid from ICEMCFD. and then employed CFX5.7 and CFD-Fastran to solve the areodunamics coeeficiences(just like Cl,Cd,Mz.....). But results from this two solver were not agreed with the experiment datas,and they were not agree with each other????????? I want to know why????

Twiti February 27, 2005 02:02

Re: A bout difference between CFX and CFD-Fatran
 
It's reasonable of the differences results you've got by experimental & numerical methods. There may be many reasons for thoes differences. 1)different boundary conditions between CFD & experimental, especially when the flow is turbulent. 2) different solving methods of CFDs. 3) uncertainty of experiments. 4)numerial errors. And so on... Basically, the experimental results are more relialbe.

Charles February 28, 2005 04:19

Re: A bout difference between CFX and CFD-Fatran
 
I have done (many) aerodynamic simulations with both CFX and CFD-Fastran. In my experience I was able to get good agreement with subsonic experimental and "standard" published results for Lift and Moment from both codes. Drag is much more difficult, because very few turbulence models can approximate the effect of transition. CFX's transition model does a better job of this than the others though. We did try CFX on transonic flows, and it wasn't as satisfactory as Fastran.

w0er March 2, 2005 06:19

Re: A bout difference between CFX and CFD-Fatran
 
Thank you,Charles,I agree with you,I have tried and found that,after i refined the grid.Drag changed a lot.Lift and Moment agreed much better.


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