## THE PRESSURE FIELD

The pressure field shows positive (reddish) values on the lower face of the wing and negative (yellow-green-blue) values on the upper face, thus leading to a lift.

Note that for large values of the angle of attack a strong negative (blue) peak of the pressure appears on the upper face of the airfoil close to the leading edge. As this negative peak increases, the positive pressure gradient downstream of it increases, a condition that leads to boundary layer separation on the upper face and consequently to a sudden drop in the lift (stall).