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Harrell's Blog


The Easy And True Solution Of Colebrook-White Equations

Posted by Harrell , 14 October 2015 - - - - - - · 6,028 views

There are about 6 different equations. Mode 2.51 is… 1/sqrt(f)=-2*Log(Rr/3.7+2.51/(Re*sqrt(f))) Mode 1.74 is… 1/sqrt(f)=1.74-2*Log(2*Rr+18.7/(Re*sqrt(f))) Mode 1.14 is… 1/sqrt(f)=1.14+2*Log(1/Rr)-2*Log(1+(9.3/(Re*Rr*sqrt(f))) Mode 9.35 is… 1/sqrt(f)=1.14-2*Log(Rr+9.35/(Re*sqrt(f))) Mode 3.71 is… 1/sqrt(...


A Different View Of Harrell's Colebrook-White Solution

Posted by Harrell , in Technical 01 October 2011 - - - - - - · 5,926 views
solution, white, view, different and 1 more...
For some reason, most people still do not understand how my Colebrook-White solution works.

It has been tested, and re-tested over and over, and always gets the right answers if you don't make
a weird error.

This may help those who are questioning "Why does it work?"

In the Wikipedia you can read about the Lambert W function. Here's a...


Harrell's "funnel" To The Colebook-White Solution.

Posted by Harrell , in Technical 27 September 2011 - - - - - - · 4,541 views
colebrook, white, solution and 1 more...
This is a PDF file with some tables and plots, to show visually how my method works. I call it a funnel, because the procedure quickly guides to maximum accuracy. You will see that after step 2, the accuracy will be amazing. I already knew the solution to the Re and Rr would give 1/sqrt(f) about 4, so I plotted initial guesses of from -4 (that is a...


How Fast Is Harrell's Colebrook-White Solution?

Posted by Harrell , in Technical 26 September 2011 - - - - - - · 4,203 views
colebrook, white, solution
This attachment is for others test my solutions and test it's speed. On those last postings I showed how my solution works step by step.

In those spreadsheets you enter Right side of the selected equation with the Reynolds number and relative
roughness and a "guess" for the "1/sqrt(f)" variable. I suggested 3 for a guess so that the...


A New Simplified, Accurate, Method For Colebrook Equations

Posted by Harrell , in Technical 16 September 2011 - * * - - - · 10,167 views
factors, darcy, friction and 1 more...
A New Simplified, Accurate, method for Colebrook equations
by Harrell Geron, NRCS Civil Engineer

This is the most simple and accurate solution for the Darcy Friction Factor with Excel. It works with the popular Colebrook-White equations. After learning this method, you can design your own procedures.

Here are four Colebrook-White equations written to...

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