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Unformatted text preview: the flow is laminar, since Re is less than 2300.
You could use the laminarflow friction factor, Eq. (6.83)
flam 96
ReDh 96
1200 100 (6.0)2
0.4 2(32.2) v   hf 0.08 and v from which p 1.9(32.2)(11.2) eText Main Menu  Textbook Table of Contents 0.08
11.2 ft
684 lbf/ft2  1200; there Study Guide Ans. (b) 362 Chapter 6 Viscous Flow in Ducts
Alternately you can finesse the Reynolds number and go directly to the appropriate laminarflow
formula, Eq. (6.79)
h2 p
3L V
or p 3(6.0 ft/s)[0.0038 slug/(ft s)](100 ft)
(0.1 ft)2 and hf p
g 684 slugs/(ft s2) 684
1.9(32.2) 684 lbf/ft2 11.2 ft This is one of those — perhaps unexpected — problems where the laminar friction is greater than
the turbulent friction. Consider steady axial laminar flow in the annular space between two concentric cylinders, as in Fig. 6.15. There is no slip at the inner (r b) and outer radius (r a). For
u u(r) only, the governing relation is Eq. (6.34) Flow through a Concentric
Annulus du
d
r
dr
dr Kr K d
(p
dx gz) (6.90) Integrate this twice
u 1 2K
r...
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 Spring '08
 Sakar

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