u = U∞ Hu 1 1. Velocity profiles are measured at the upstream (station 1) and downstream (station 2) end of the control volume as shown below. The flow is incompressible, two-dimensional, and steady. If surfaces 3 and 4 are streamlines, express the vertical dimension H₁ of the upstream section in terms of the vertical dimension Ha of the downstream section (Hint: use conservation of mass). What is the force acting on the airfoil? Streamline 3 2 Streamline = U₂ (1- 0.5 cos пу 2HD