Return to the flow past a flat plate at an incidence (Figure 3.55a). According to the general theory of two-dimensional potential flows, the resultant pressure force acting on the plate should be...

Return to the flow past a flat plate at an incidence (Figure 3.55a). According to the general theory of two-dimensional potential flows, the resultant pressure force acting on the plate should be directed perpendicular to the free-stream velocity vector (see Section 3.4.3). On the other hand, the pressure on the lower and upper sides of the plate produces a force directed perpendicular to the plate surface. Therefore, common sense suggests that resultant force should also be directed perpendicular to the plate, not to the free-stream velocity. How can this dilemma be resolved?