A new criteria for estimating composite roughness on hydraulic models

Abstract

Practical engineering has considered that implicit Colebrook-White equation has been the standard for estimating pipe friction factor in a fully developed turbulent regime in conductions manufactured with one material. Due to the implicit character of the criteria, several authors have developed some criteria that use other kind of solutions like presented by Elfman (2005) who takes as basis Nikuradse criteria. In this study, a new methodology is proposed with basis in Colebrook equation for tunnels with composite roughness. Considering hydraulic models build by the authors for diversion works (El Cajón and La Yesca), the analysis is made, and is concluded that this Colebrook analysis is more scientific, and applicable to this kind of works.