Question: Static pressure is measured at a number of points on the surface of a long circular cylinder of 150 mm in diameter with its axis perpendicular to a stream of standard density at 30 ms-1 . The pressure points are defined by the angle θ, which is the angle subtended at the center by the arc between the pressure point and the front stagnation point. In the table following, values are given for p - p0, where p is the pressure on the surface of the cylinder and p - p0 is the undisturbed pressure of the free stream, for various angles θ, all pressures being in Nm-2. The readings are identical for the upper and lower halves of the cylinder. Estimate the form pressure drag per meter run and the corresponding drag coefficient.
For values of θ between 120 and 180 degrees, p - p0 is constant at -569 N m-2.