6-6. Drag on a Cylinder at High Reynolds Number Consider flow perpendicular to the axis of a long cylinder at high Re. The cylinder radius is R, the relative velocity is U, and Re is based on the cylinder diameter. Figure P6-6 shows pressures measured at the surface of a cylinder for Re=1.86105 and an approximate fit to those data. Figure P6-6. Pressure at the surface of a cylinder during transverse flow at high Re. The ordinate is /(U2/2) and the angle is measured from the upstream stagnation point. Included are experimental results for Re=1.86105, an approximate fit to those data (see text), and the predietion for irrotational flow. The data are due to O. Flachsbart, as presented in Schlichting (1968, p. 21), and the solution for irrotational flow is derived in Example 9.3-1. Also shown is the prediction for irrotational flow. The abscissa () is angular position relative to the most upstream point on the surface. The fit is the piecewise function given by U2/2P(R,)={138sin21for0/3for/3. (a) Using the expression suggested above (or another suitable fit to the data), calculate F9 for a cylinder of length L. (b) The drag coefficient for transverse flow past a cylinder is defined as CD=FD/(U2LR), Compare the value of CD from a standard chart (e.g., Denn, 1980, p. 66) with the pressure contribution obtained from part (a). At the given value of Re, approximately what fraction of FD is caused by form drag