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-   -   Cl, Cd, Reference Values in 2D? (

sniperees October 12, 2011 12:37

Cl, Cd, Reference Values in 2D?
Hi there,

I'm fairly new to fluent so bear with me.

Let me explain my situation:

I am doing a 2D simulation of airfoils (to be more specific NACA 4421 and NACA 23012) and I am confused with what the Cd and Cl are in terms of. Is the Cd and Cl displayed while the simulation is running in units of per meter?

Also, what should my reference area be? My chord length is 2, however, there are alot of opinions that say that the reference area should be the chord length, others that say that it should be the chord length squared.

If you could give any input, that would be great!



k_k October 20, 2011 13:04


Use the chord length as the ref length.
Cl and Cd are non dimensional and it cannot not said to be per m. 2D flow simulation over an aerofoil is analogous to flow past a wing of infinite span.

Also make sure that you set the reference pressure correctly.


m2montazari October 20, 2011 18:04

in 2d simulations dept=1,length=chord,area=chord
and about cl,cd,cm reference pressure is not important but reference velocity and density should be checked.

jafarizade October 21, 2011 10:47

in such a problem for a 2d prblem and for cd and cl refreance values for velocity,density,area and viscosity should be checked!

rajaprathap July 2, 2016 03:09

about cd
iam getting negative values for cd when trying to simulate flow over 2d airfoil.pls explain how to sort out this issue

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