Question
Indirect method In CAD
Example 1.7: The Colebrook equation is given by ED 2.51 Find the friction factor f for NR.-6.5 × 104 and E/D = 0.00013. As the first guess for f, use fo = 0.1. Solution
0 0
Add a comment Improve this question Transcribed image text
Answer #1

Colebrook Equation Given 65000 0.00013 Intial Guess Iteratively Calculating the value Guess Value of f LHS RHS Difference Guess Value of f LHS RHS Difference Guess Va LHS RHS Difference Guess Va LHS RHS Difference 0.1 3.16228 7.53161 4.36933 0.09 3.33333 7.49622 4.16289 0.08 3.53553 745619 3.92066 0.07 3.77964 7.41022 3.63057 0.06 4.08248 7.3564 3.27392 0.05 4.47214 7.29177 2.81963 5 7.2113 2.2113 0.03 5.7735 7.10552 1.33202 0.02 7.07107 6.95293 -0.11814 10 6.68408-3.31592 0.03 5.7735 7.10552334 1.33202065 0.029 5.8722 7.0929158 1.22071361 0.028 5.97614 7.07983558 1.10369253 0.027 6.08581 7.06624758 0.98044138 .026 6.20174 7.05211269 0.85037596 0.025 6.32456 7.03738715 0.71283183 0.024 6.45497 7.02202179 0.56704955 0.023 6.5938 7.0059611 0.41215637 0.022 6.742 6.98914207 0.24714345 .021 6.90066 6.97149284 0.07083725 0.02 7.07107 6.9529309 -0.1181369 0.021 6.90066 6.97149 0.07084 0.0209 6.91714 6.96968 0.05253 0.0208 6.93375 6.96786 0.0341 0.0207 6.95048 6.96602 0.01554 0.0206 6.96733 6.96418-0.00315 0.0205 6.9843 6.96233-0.02197 0.0204 7.0014 6.96047 -0.04093 0.0203 7.01862 6.9586-0.06002 0.0202 7.03598 6.95672 -0.07925 0.0201 7.05346 6.95483 -0.09863 0.02 7.07107 6.95293-0.11814 0.0207 6.95048 6.96602 0.01554 0.02069 6.95216 6.96584 0.01368 0.02068 6.95384 6.96566 0.01182 0.02067 6.95552 6.96547 0.00995 0.02066 6.95721 6.96529 0.00803 0.02065 6.95889 6.9651 0.00621 0.02064 6.96058 6.96492 0.00434 0.02063 6.96226 6.96474 0.00247 0.020626.96395 6.96455 0.0006 0.02061 6.96564 6.96437 -0.00127 0.0206 6.96733 6.96418 -0.00315 0.04 Using the solver from data section Guess Value of f LHS RHS Difference 0.02061679 6.96449 6.96449 -1E-13Note: Using the excel sheet, one can find the friction factor f easily. In the first case, I have solved manually by the fact that the left-hand side (LHS) of the Colebrook equation is equal to the right-hand side (RHS). If the sign of the value changes from negative to positive the value of friction factor lies in between that so again iterate between that value (see above excel sheet).

In the second case, I have used solver to solve for friction factor f. In Excel go to date--> pick the solver --> select the set target cell (your difference column) --> Equal To: Value of 0 --> By Changing Cells (your Guess value of f) --> Options --> Convergence (0.000001) --> tick to Use Automatic Scaling --> Estimates (Quadratic) --> Ok --> solve --> Now you will get the value of friction factor f

Hence the friction factor f value here is 0.02061679

Add a comment
Know the answer?
Add Answer to:
Indirect method In CAD Example 1.7: The Colebrook equation is given by ED 2.51 Find the...
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for? Ask your own homework help question. Our experts will answer your question WITHIN MINUTES for Free.
Similar Homework Help Questions
ADVERTISEMENT
Free Homework Help App
Download From Google Play
Scan Your Homework
to Get Instant Free Answers
Need Online Homework Help?
Ask a Question
Get Answers For Free
Most questions answered within 3 hours.
ADVERTISEMENT
ADVERTISEMENT