At the risk of oversimplifying, the thickening causes an increase in the drag, while the decambering causes a reduction in lift. This procedure amounts to effectively modifying the airfoil geometry, the major effects being a thickening and a decambering of the foil section.
Inviscid flow and boundary-layer calculations are performed in an iterative process, with the boundary between the viscous and inviscid regions determined by moving the points on the airfoil surface in the normal direction, by an amount equal to the computed displacement thickness of the boundary layer.
These are based on the idea that the viscous effects are confined to a limited region near the airfoil surface (the boundary layer), with no pressure gradients normal to the surface, and with inviscid flow outside the region.
#HOW IS LIFT CREATED WITH AN AIRFOIL FULL#
I would like to add a few comments about the effective modification of the airfoil shape due to the boundary layer (since the question specifically asked about that).Īt sufficiently high Reynolds numbers, flows over airfoils can be computed (to engineering accuracy) using viscous/inviscid interaction techniques, rather than solving the full Navier-Stokes equations. The answer by tpg2114 does a good job of explaining why the loss of energy in the flow due to viscous effects should result in a reduction in lift.