Default fluid type in XFOIL
 

Hello

I encountered a problem when I am trying to do some calculation with XFOIL.

I did some measurements with an airfoil in a wind tunnel. And now, I would like to do some calculations with XFOIL using the same configurations as in the measurements.

Since XFOIL gives CL CD directly, I think it is necessary to know the type of fluid (in order to use the right \rho). How can I check that? Or is it possible to change the fluid type to air?

Maybe I am wrong...Please enlighten me. Thank you very much.

Hi,

When you use XFoil, if defining a viscuous calculation, you have to set the Reynolds number and Mach of the simulation. That's the only way you define your fluid, and it should be enought.

Thank you for your reply...

I still have some doubts...If the fluid type is only defined this way, how would XFOIL calculate CL CD? Since we need F/(0.5\rho U^2 S) to get CL CD, right?
Or does it calculate those another way?

Thank you

You dont have to know the fluid type. maybe you can check Drela's paper, Section 3. http://web.mit.edu/drela/Public/papers/xfoil_sv.pdf