Lift and Drag from Pressure Distribution over an Air Foil

1. May 13, 2010

Triggers12

Pretty simple question:

Is it possible to completely calculate Lift and Drag from the pressure distribution over an airfoil?

Atm, I have Lift worked out as well as the Induced drag ( correct me if I'm wrong. ) but am having trouble working out how it would be possible to get the skin friction / parasitic drag.

Trigs

2. May 13, 2010

rcgldr

How would you determine the pressure distribution over an airfoil? Perhaps some form of intrumentation, but that would have some effect on the flow. A simplified model could use static pressure distribuition and the normals (line perpendicular) to the sections of surface of a wing, but there are other factors. Static pressure isn't directional, but dynamic pressure and any related changes in momentum of the air are directional. Skin friction is nearly parallel to a wing surface. The shear boundary layer thickens over time, may detach and reattach as it transitions from laminar to turbulent, so that changes the effective air foil shape.

The best mathematical models for lift and drag are usually based on some simplified form of Navier Stokes equations:

http://en.wikipedia.org/wiki/Navier–Stokes_equations

Last edited: May 13, 2010
3. May 13, 2010

Triggers12

Hey thanks for the response,

Trigs

Last edited by a moderator: Jun 25, 2010