Philip M. Gerhart, Andrew L. Gerhart, John I. Hochstein
ISBN #9781119080701
8th Edition
1,309 Questions
Homework Questions
This section delves into the flow over immersed bodies with a focus on analyzing external flow characteristics including lift and drag. It provides an in-depth exploration of boundary layer behavior—from the initial laminar development described by the Prandtl-Blasius solution to the complexities of turbulent flow and the effects of pressure gradients. Additionally, the section outlines methods to compute drag forces, crucial in evaluating the performance of various engineering structures. The key takeaway is the integration of theoretical models and practical calculations to predict and enhance the behavior of fluid flows around immersed bodies.
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CONCEPT
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Assume that water flowing past the equilateral triangular bar shown in Fig. $\mathrm{P} 9.1$ produces the pressure distributions indicated. Determine the lift and drag on the bar and the corresponding lift and drag coefficients (based on frontal area). Neglect shear forces.
Fluid flows past the two-dimensional bar shown in Fig. P9.2. The pressures on the ends of the bar are as shown, and the average shear stress on the top and bottom of the bar is $\tau_{\mathrm{avg}}$. Assume that the drag due to pressure is equal to the drag due to viscous cffects. (a) Determine $\tau_{\text {ave }}$ in terms of the dynamic pressure, $\rho U^{2} / 2$ (b) Determine the drag coefficient for this object.
Repeat Problem 9.1 if the object is a cone (made by rotating the equilateral triangle about the horizontal axis through its tip) rather than a triangular bar.
The average pressure and shear stress acting on the surface of the 1 -m-square flat plate are as indicated in Fig. $P 9.4$. Determine the lift and drag generated. Determine the lift and drag if the shear stress is neglected, Compare these two sets of results.
The pressure distribution on the 1 -m-diameter circular disk in Fig. $\mathrm{P} 9.5$ is given in the table. Determine the drag on the disk.