2D Lift and Drag Coefficients for Airfoil

[corsair2014]

So this is a fairly simple question (I hope). How would you calculate the 2d coefficients for an airfoil? In other words, I can run a 2d simulation in CFD (2018) and get a lift and drag force (x and y) from the wall calculator. Now, how do those relate to the Coefficients? I.e. how is CFD 2018 getting these force values; is it assuming a 'wingspan' (z) of 1 meter or?

The driving equations are Force = 0.5*density*velocity^2*area*coefficient (lift or drag). So what is that "area" that CFD 2018 is assuming to get a force? Once I know that, I can backsolve for the coefficients. 

Thank you!

[Anonymous · Accepted solution]

I know that a 2d analysis is equivalent to a 3D analysis of the same exact cross-section with a 1 unit length thickness + slip/symmetry walls

[corsair2014]

Thanks for the reply! So if i have a simulation setup in "feet", it will simulate a wing that spans wall-to-wall with a span of 1 foot?

[Anonymous]

Yes

Autodesk webinar about 2d modeling here

https://youtu.be/CoGTvfUnfO4

[corsair2014]

Okay and what does the program use for 'area' in the lift equation for 2d? Surface area of the side of the airfoil, or total surface area of the model if extrapolated 1 unit length?

[Anonymous]

Hi, 

I never really went deep into 2d analysis, neither aero drag and lift, so I'll make a guess here. When you use the wall calculator, you are selecting an edge, so the surface area used to calculate a force would be this edge length x 1 unit length. 

To confirm, perhaps you could investigate with a simple 2d square shape where there's no unknowns, and do some easy test and backsolve everything

One more webinar on 2d airfoil if you haven't watch it:

https://www.youtube.com/watch?v=N4z8HcBtL6U

And this section on user's guide:

http://help.autodesk.com/view/SCDSE/2019/ENU/?guid=GUID-C8165A4A-97E0-43BC-90BC-A179DDE9FB6A

I have no time to dig up more useful infos on the subject, but maybe the forum has interesting threads about it? I recall you are not the first one working on 2D lift and drag.

[Anonymous]

I forgot this tool that might be interesting for your work. 

Wall forces tool around 30min 

https://youtu.be/miUqMOk5PJU?t=1761

[user10068]

Can someone guide me on how to measure the lift and drag of a 3-D airfoil using this software? I'm new to autocad and i'm having a really hard time using the CFD software