Harrell's Blog

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(...

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...

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
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...