Wall similarity in turbulent open-channel flow

Fabián López, Marcelo H. García

Research output: Contribution to journalArticle

Abstract

The present work demonstrates that the assumption of wall similarity in the equilibrium region of open channels leads to the definition of a constant, universal value for the normalized vertical flux of turbulent kinetic energy irrespective of wall roughness. Moreover, by additionally assuming a gradient-flux model for the turbulent kinetic energy, its bed-normal distribution is easily estimated by an expression with parameters that rely on a physical basis. Turbulence measurements performed in smooth-, transitionally rough-, and fully rough-bed (sandgrain) open channels confirm this hypothesis, providing at the same time an alternative way of determining the lower and upper limits of the intermediate region. Finally, based upon wall-similarity assumptions, a new methodology is proposed for estimating mean bed-shear velocities (stresses) in free-surface flows at high local and global Reynolds numbers, irrespective of roughness condition at the bed.

Original languageEnglish (US)
Pages (from-to)789-796
Number of pages8
JournalJournal of Engineering Mechanics
Volume125
Issue number7
DOIs
StatePublished - Jan 1 1999

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering

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