Volume 19, Numéro 1, Pages 219-227

Analytical Relationship Between The Strickler Roughness Coefficient And The Absolute Roughness In Rough Turbulent Flow Regime

Authors : Achour Bachir . Amara Lyes .


Manning-type relations do not contain the term viscosity, which limits their use to the field of rough turbulent flow. Strickler roughness coefficient k or n of Manning are estimated with great difficulty, requiring a proven practical experience. In order to simplify the problem and allow a rapid calculation of k, the main objective of the present study is to establish an explicit analytical relation which links k and the absolute roughness . To do this, it was useful to combine the rational Darcy-Weisbach relationship and the empirical Manning-Strickler formula. After some development, the function , where is the relative roughness, was clearly defined. It was possible to calculate the mean value of the function  in the practical range of such that  is equal to a constant. This constant is different from that proposed by the literature.


Darcy-Weisbach ; Friction factor ; Manning-Strickler ; Relative roughness ; Rough turbulent flow ; Roughness coefficient