A power-law approximation of the turbulent flow friction factor useful for the design and simulation of urban water networks

Koutsoyiannis, D

dc.contributor.author	Koutsoyiannis, D	en
dc.date.accessioned	2014-03-01T01:27:47Z
dc.date.available	2014-03-01T01:27:47Z
dc.date.issued	2008	en
dc.identifier.issn	1573-062X	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/18570
dc.subject	Colebrook-White equation	en
dc.subject	Darcy-Weisbach equation	en
dc.subject	Friction factor	en
dc.subject	Manning equation	en
dc.subject	Pipe flow	en
dc.subject	Power law	en
dc.subject	Urban water networks	en
dc.subject.other	Approximation theory	en
dc.subject.other	Friction	en
dc.subject.other	Pipe flow	en
dc.subject.other	Surface roughness	en
dc.subject.other	Turbulent flow	en
dc.subject.other	Darcy law	en
dc.subject.other	friction	en
dc.subject.other	numerical model	en
dc.subject.other	pipe flow	en
dc.subject.other	power law	en
dc.subject.other	turbulent flow	en
dc.subject.other	Willia	en
dc.title	A power-law approximation of the turbulent flow friction factor useful for the design and simulation of urban water networks	en
heal.type	journalArticle	en
heal.identifier.primary	10.1080/15730620701712325	en
heal.identifier.secondary	http://dx.doi.org/10.1080/15730620701712325	en
heal.language	English	en
heal.publicationDate	2008	en
heal.abstract	An approximation of the friction factor of the Colebrook-White equation is proposed, which is expressed as a power-law function of the pipe diameter and the energy gradient and is combined with the Darcy-Weisbach equation, thus yielding an overall power-law equation for turbulent pressurised pipe flow. This is a generalised Manning equation, whose exponents are not unique but depend on the pipe roughness. The parameters of this equation are determined by minimising the approximation error and are given either in tabulated form or as mathematical expressions of roughness. The maximum approximation errors are much smaller than other errors resulting from uncertainty and misspecification of design and simulation quantities and also much smaller than the errors in the original Manning and the Hazen-Willians equations. Both these can be obtained as special cases of the proposed generalised equation by setting the exponent parameters constant. However, for large roughness the original Manning equation improves in performance and becomes practically equivalent with the proposed generalised equation. Thus its use, particularly when the networks operate with free surface flow is absolutely justified. In pressurised conditions the proposed generalised Manning equation can be a valid alternative to the combination of the Colebrook-White and Darcy-Weisbach equations, having the advantage of simplicity and speed of calculation both in manual and computer mode.	en
heal.publisher	TAYLOR & FRANCIS LTD	en
heal.journalName	Urban Water Journal	en
dc.identifier.doi	10.1080/15730620701712325	en
dc.identifier.isi	ISI:000262437200003	en
dc.identifier.volume	5	en
dc.identifier.issue	2	en
dc.identifier.spage	107	en
dc.identifier.epage	115	en