Explicit solutions for turbulent flow friction factor: A review, assessment and approaches classification

Discussion of “Accurate and Efficient Explicit Approximations of the Colebrook Flow Friction Equation Based on the Wright ω-Function” by DejanBrkić; and Pavel Praks, Mathematics 2019, 7, 34; doi:10.3390/math7010034

“…The iterative methods require a great deal of time, and the graphical solutions are not accurate and are limited. To alter the implicit Colebrook-White equation, several authors have proposed an explicit solution to avoid such difficulties and weaknesses in the above methods [3].…”

“…In this section the discussers would like to propose an improvement of the results proposed by the authors to reach a very accuracy results compared to best explicit formulas obtained by Vatankhah AR (2014) [3,6], where the maximum error is 0.146%.…”

“…Several researchers tried to propose an exact solution of the Colebrook-White equation (which is relevant only for turbulent flow [1,7])with the hope of achieving zero-percent (0%) maximum deviation as proposed in similar research [8][9][10], however simple formulas are always be preferred for highly computationally efficient [1,3]. The authors have presented an interesting work where the Right ω-function and the Padé approximation were used.…”

“…Three criteria were proposed by Zeghadnia et al (2019) [3] to assess the accuracy of the explicit solutions for the turbulent flow friction factor, where many steps must be followed:…”

Accurate and Efficient Explicit Approximations of the Colebrook Flow Friction Equation Based on the Wright ω-Function: Reply to Discussion

“…-We are concerned that disputed accuracy of some of our findings is based on the paper [8], which is written by the same authors as the discussion paper [2]. In [8], authors claim that explicit approximations of the Colebrook equation given by Serghides [9] and Buzzelli [10] are very inaccurate.…”