nYes, this is one reason why your lift and drag coefficients are way off.nThe Velocity Specification Method is not correct. The air is coming in normal to the semi-circle, that is directed toward the center of the circle where it collides with the wing.nYou want Components. You want the air coming in parallel to the X axis in a nice smooth air stream.nPut 20 m/s in the X component and 0 m/s in the Y component.n