fluid_mechanics

8V
Viscous Flow
in Pipes
CHAPTER OPENING PHOTO: Turbulent jet: The jet of water from the pipe is turbulent. The complex, irregular,
unsteady structure typical of turbulent flows is apparent. (Laser-induced fluorescence of dye in water.) (Photography
by P. E. Dimotakis, R. C. Lye, and D. Z. Papantoniou.)
Learning Objectives
V8.1 Turbulent jet
After completing this chapter, you should be able to:
■ identify and understand various characteristics of the flow in pipes.
■ discuss the main properties of laminar and turbulent pipe flow and appreciate
their differences.
■ calculate losses in straight portions of pipes as well as those in various
pipe system components.
■ apply appropriate equations and principles to analyze a variety of pipe
flow situations.
■ predict the flowrate in a pipe by use of common flowmeters.
Pipe flow is very
important in our
daily operations.
In the previous chapters we have considered a variety of topics concerning the motion of fluids.
The basic governing principles concerning mass, momentum, and energy were developed and applied,
in conjunction with rather severe assumptions, to numerous flow situations. In this chapter
we will apply the basic principles to a specific, important topic—the incompressible flow of viscous
fluids in pipes and ducts.
The transport of a fluid 1liquid or gas2 in a closed conduit 1commonly called a pipe if it is of
round cross section or a duct if it is not round2 is extremely important in our daily operations. A brief
consideration of the world around us will indicate that there is a wide variety of applications of pipe
flow. Such applications range from the large, man-made Alaskan pipeline that carries crude oil almost
800 miles across Alaska, to the more complex 1and certainly not less useful2 natural systems of
“pipes” that carry blood throughout our body and air into and out of our lungs. Other examples
383