reference value
Dear friends,
I am a new user of Fluent.I find it difficult for me to get accurate Cl,Cd and Cm even in very simple cases: 1.2D Euler equations Naca0012 airfoil Mach infinite = 0.8 Alpha = 1.25 degree 2.3D Euler equations M6 wing Mach infinite = 0.84 Alpha = 3.06 The Cl,Cd and Cm obtained using Fluent can be much larger or less than the values pointed by many reference.I think I choose the right refernce value. Could you tell me why? Thanks in advance. Xia Jian 
Re: reference value
First check the reference values for velocity, area... and look then at the exact fluentdefinition of cl, cd and cm in the manual. chris

Drag Predictions
Hello Xia,
I have also had difficulties predicting drag using Fluent(5). I am ultimately interested in engine intakes, but to start off ran simulations of simple 2 and 3D shapes for which I knew the drag coefficient. I found I could get the correct values for drag coefficient and drag force, but only after a lot of y+ adaption, even when I had predicted the size of the first cell as Fluent recommended. My concern is that when I am modelling something I don't have the answers for, how will I know when I reach the correct result? I would appreciate any suggestions people out there have since I know I will have more work coming up in this field. All the best and good luck with your simulations. I would be very interested to hear how you get on. Althea 
Re: Drag Predictions
Hi,
Drag coefficient is affacted by discretization order (depending your mesh)and turbulance models. My suggestion is that using high order discretization ( for example 2.order or QUICK for momentum)and powerfull turbulance models like Realizable ke. Ali, 
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