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-   -   Overpredicted cl and cd on NACA 0012 (with Fluent) (http://www.cfd-online.com/Forums/main/16413-overpredicted-cl-cd-naca-0012-fluent.html)

KevinK February 27, 2009 20:32

Overpredicted cl and cd on NACA 0012 (with Fluent)
 
Hi I am doing a practice of cl&cd prediction using NACA 0012 with Fluent. I have always obtained overprediction on both cl and cd continuously, and run out of ideas on where the problems are. cl exceeds by 20% and cd is over by 70% (at AOA 4, 5 degs)!!

I have run my cases in the following conditions:

steady-state

M=0.6 (tried 0.2 also)

Re = 2M

Fully turbulent flow (with S-A model, various viscosity ratio from 0.001 ~ 10 but no help)

unstructured mesh, but structured BL mesh

y+ on order of unity

2D mesh size 30k ~ 60k points

computation domain 100c uniformly in all directions

A continuity convergence criterion of 1e-9 cannot be reached, as the residual always hangs around on order of -6

Any comment/suggestion on improving the solution is appreciated!


Alex February 28, 2009 02:47

Re: Overpredicted cl and cd on NACA 0012 (with Flu
 
At M_infty=0.6 and AOA=4.5 deg, the flow is highly sensitive to turbulence models. Did you try SST-k-omega?

KevinK February 28, 2009 13:30

Re: Overpredicted cl and cd on NACA 0012 (with Flu
 
yes. both S-A and SST models were attempted. Results did not differ much though...


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