- An airfoil generates lift by changing the velocity of the air passing over and under itself. The airfoil angle of attack and/or camber causes the air over the top of the wing to travel faster than the air beneath the wing.
- It can be seen that the effect of the airfoil is to introduce a change in airflow, which seems to circulate around the airfoil...
- This "circulation" is the theoretical basis for the classical calculation of lift and drag-due-to-lift The the greater the circulation the greater the lift.
- Odd as it sounds, an airfoil in two-dimensional flow does not experience any drag due to the creation of lift.
- The figure below shows typical pressure distributions for the upper and lower surfaces of a lifting airfoil at subsonic speeds. Note that the upper surface of the wing contributes about two-thirds of the total lift.
AIAA further ruins the hope of any prospective CFD-user during any foreseeable future:
- No current codes actually attempt to solve the true full Navier-Stokes equations due to the difficulty of mathematical analyzing turbulence. Turbulence occurs at the molecular level, which would probably require gridding with billions of molecular sized grids.
- CFD does not replace the wind tunnel. In fact , it really doesn't even reduce the number of wind-tunnel test hours.