Chapt06

# 68 and can thus solve d when the right hand side is

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Unformatted text preview: suming that Q that d (30 cm) is unknown. Recall L 100 m, 0.06 mm are known but 2 E-5 m2/s, and hf 8 m. Iterative Solution First write the diameter in terms of the friction factor: (9.81 m/s2)(8 m)d5 8 (100 m)(0.342 m3/s)2 2 f 8.28d5 or d 0.655f 1/5 | v v in SI units. Also write the Reynolds number and roughness ratio in terms of the diameter: | e-Text Main Menu | Textbook Table of Contents | Study Guide (1) Chapter 6 Viscous Flow in Ducts 4(0.342 m3/s) (2 E-5 m2/s)d Red 21,800 d (2) 6 E-5 m d d (3) Guess f, compute d from (1), then compute Red from (2) and /d from (3), and compute a better f from the Moody chart or Eq. (6.64). Repeat until (fairly rapid) convergence. Having no initial estimate for f, the writer guesses f 0.03 (about in the middle of the turbulent portion of the Moody chart). The following calculations result: f 0.03 0.655(0.03)1/5 d Red 21,800 0.325 67,000 fnew 0.0203 then Red,new 72,500 fbetter 0.0201 Eq. (6.54): Eq. (6.54): d 0.325 m 1.85 E-4 d dnew 0.301 m 2.0 E-4 and d 0.300 m Ans. The procedure has converged to the correct diameter of 30 cm given in Example 6.9. EES Solution For an EES solution, enter the data and the appropriate equation...
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