Philip M. Gerhart, Andrew L. Gerhart, John I. Hochstein
ISBN #9781119080701
8th Edition
1,309 Questions
Homework Questions
This chapter addresses the complex nature of viscous flow in pipes by differentiating between laminar and turbulent flow regimes and exploring the concept of fully developed flow. It presents various methods—ranging from direct force balance and the Navier-Stokes equations to dimensional analysis and energy considerations—to derive flow characteristics. A significant focus is placed on understanding pressure losses (both major and minor) and practical methods for flowrate measurement. The comprehensive exploration enhances understanding of both theoretical and applied aspects of pipe flow in engineering contexts.
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Under normal circumstances is the airflow though your trachea (your windpipe) laminar or furbulent? List all assumptions and show all calculations.
Rainwater runoff from a parking lot flows through a 3-ft-diameter pipe, completely filling it. Whether flow in a pipe is laminar or turbulent depends on the value of the Reynolds number. (See Video V8.2.) Would you expect the flow to be laminar or turbulent? Support your answer with appropriate calculations.
Blue and yellow streams of paint at $60^{\circ} \mathrm{F}$ (each with a density of 1.6 slugs/ft $^{3}$ and a viscosity 1000 times greater than water) enter a pipe with an average velocity of 4 ft as shown in Fig. P8.3. Would you expect the paint to exit the pipe as green paint or separate streams of blue and yellow paint? Explain. Repeat the problem if the paint were "thinned" so that it is only 10 times more viscous than water. Assume the density remains the same.
Air at $200^{\circ} \mathrm{F}$ flows at standard atmospheric pressure in a pipe at a rate of $0.08 \mathrm{lb} / \mathrm{s}$. Determine the minimum diameter allowed if the flow is to be laminar.
To cool a given room it is necessary to supply $4 \mathrm{ft}^{3} / \mathrm{s}$ of air through an 8 -in.-diameter pipe. Approximately how long is the entrance length in this pipe?