# Colebrook-White Equation Calculator

## Calculates the root of Colebrook-White Equation using Simple and TRUE method.

 Colebrook-White Equation mode 2.51 mode 1.74 mode 1.14 mode 9.35 mode 3.71 mode 3.72 Rr Rn 6digit10digit14digit18digit22digit26digit30digit34digit38digit42digit46digit50digit Loops f Left Right
 $\normal Simple\ and\ TRUE\ method\\[10](1)\ X=-2\log(\frac{Rr}{3.7}+\frac{2.51}{Rn}X)\hspace{20}at\ mode\ 2.51\\(2)\ X_0=3\\\hspace{25} X_{n+1}=-2\log(\frac{Rr}{3.7}+\frac{2.51}{Rn}X_{n})\\$The Simple and TRUE method is provided by Harrell Geron as a Federal NRCS, USDA engineer.
Colebrook-White Equation
 [1-5] /5 Disp-Num5103050100200
[1]  2014/11/07 02:56   Male / 30 years old level / A teacher / A researcher / Very /
Purpose of use
For teaching purposes:

--> comparison of solution obtained by means of Moody's Diagram and iterative solution of Colebrook - White equation.

--> so that my students can calculate faster the pressure drop in buildings instalations
Comment/Request
Thanks for the calculator!!

Maybe not too bad, but the solution given for Re < 2000 is not equal to 64/Re. I know it is not necessary to use the Colebrook - White equation in this case, but anyway, it should give an accurate solution, isn't it?
[2]  2014/05/09 12:34   Male / 60 years old level or over / An office worker / A public employee / A little /
Purpose of use
to check manual calculation
Comment/Request
please calculate using Colebrook-White equation the
maximum flow capacity & velocity of
pipe size 0.225m. diameter vitrified clay pipe
[3]  2013/11/01 03:27   Male / 60 years old level or over / An engineer / Very /
Purpose of use
If the user selects a mode other that 2.51, then the display of the mode would be good. But it only shows the 2.51 mode.

Also you said you were using 3.71 where I had emailed the "Rr/3.7", but you were using the 3.71 mode.

Today someone asked for the "9.35" mode. and I showed them how, but the screen showed the 2.51 mode, and they wanted to see that equation.

from Keisan
We have changed to be displayed the formula corresponding to the selected mode.
[4]  2013/10/04 00:37   Male / 60 years old level or over / A engineer / Very /
Comment/Request
I tried the Newton compute again, and noticed I could set it for 50 digits like I did.
I did 3 random Rr and Rn and found out that the Newton gets the same answer as I do for 50 digits.
I checked the left and right for each and found they have the same "checked" values also.

I want the Public to learn my easy and true solution, then they could compute their own designs.
[5]  2013/10/02 10:02   Male / 50 years old level / A engineer / Very /
Purpose of use
The Newton method is fair, but not exactly right.

Here's my easy solution. It works in Excel for 15 digits. Your computer shows 50 digits and it proves I am right. Here's that Rn, and Rr solved

Rn=604133;
Rr=0.01002;
A=Rr/3.7;
B=2.51/Rn;
Loops=0;
D=3; do {X=-2*log(A+B*D);
Loops=Loops+1;
D=-2*log(A+B*X);} while (X<>D);
f=1/X/X;
Left=1/sqrt(f);
Right=-2*log(Rr/3.7+2.51/Rn/sqrt(f));
Loops;
f;
Left;
Right;

10 loops
f= 0.038030096166348760840839356634286786195821313985827

left side of equation '5.1278615179514698534039181406746481344220332448845

right side of equation '5.1278615179514698534039181406746481344220332448845

Left=Right so it is proved right.
Comment/Request
Post this to everyone
My Excel training is
colebrook-white.blogspot.com

Thanks, Your computer helps me prove I am right.
from Keisan
We changed Rr/3.7 instead of Rr/3.71 in Colebrook-White Equation.
New results are the same as your results.
1/sqrt(f))=-2*log(Rr/3.7+2.51/Rn/sqrt(f))

Sending completion

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