Civil Engineers with Experience Using the Colebrook Equation?

[Fred Lusk]

I am a civil engineer with more than 40 year's consulting experience. My experience is mostly municipal infrastructure, including a lot of modeling and design of water distribution systems.

I don't use Darcy-Weisbach and Colebrook-White all that often, sticking mostly with Hazen-Williams and Manning's. When I do use Colebrook-White, I sometimes iterate (HP-41CX, HP-42S, DM-42, Excel, and Mathcad), but I mostly use an the explicit approximation equation. About two dozen explicit approximation equations have been published--some excellent, some good, some fair, and some poor--and I have my favorites. I have had a long-time interest in the explicit approximations since running across the Blasius Equation in college.

Back in 2014, I published on the PTC Mathcad forums a very thorough analysis of the explicit approximation equations I had found. Here is a link to that post: https://community.ptc.com/t5/PTC-Mathcad...m-p/450068 . The attached .zip file includes .pdf files for those who don't have Mathcad. The two worksheets (one for smooth pipe approximations and one for everything else) also solve Colebrook-White using Mathcad's solver and it's that solution that forms the basis for comparing the explicit approximations.

While the Mathcad solution won't necessarily be useful for programming a calculator, you may find the rest of the analysis useful for practical hydraulic calculations.