The results of a wind tunnel test to determine the drag on a body (see Fig. P5.65) are summarized below. The upstream [section (1)] velocity is uniform at \(100 \mathrm{ft} / \mathrm{s}\). The static pressures are given by \(p_{1}=p_{2}=14.7 \mathrm{psia}\). The downstream velocity distribution, which is symmetrical about the centerline, is given by

\[ \begin{array}{ll} u=100-30\left(1-\frac{|y|}{3}\right) & |y| \leq 3 \mathrm{ft} \\ u=100 & |y|>3 \mathrm{ft} \end{array} \]

where \(u\) is the velocity in \(\mathrm{ft} / \mathrm{s}\) and \(y\) is the distance on either side of the centerline in feet (see Fig. P5.65). Assume that the body shape does not change in the direction normal to the paper. Calculate the drag force (reaction force in \(x\) direction) exerted on the air by the body per unit length normal to the plane of the sketch.

Figure P5.65

Transcribed Image Text:

Section (1) V = 100 ft/s Body 3 ft 3 ft Section (2) V = 100 ft/s