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Finite-amplitude alternate bars

Published online by Cambridge University Press:  21 April 2006

M. Colombini
Affiliation:
Istituto di Idraulica, Facoltà di Ingegneria, Genova, Italy
G. Seminara
Affiliation:
Istituto di Idraulica, Facoltà di Ingegneria, Genova, Italy
M. Tubino
Affiliation:
Istituto di Idraulica, Facoltà di Ingegneria, Genova, Italy

Abstract

Following ideas developed in the field of hydrodynamic stability of laminar flows (Stuart 1971) a predictive theory is proposed to determine the development of finite-amplitude alternate bars in straight channels with erodible bottoms. It is shown that an ‘equilibrium amplitude’ of bedforms is reached as t → ∞ within a wide range of values of the parameter (β − βc)/βc, where t is the time, β is the width ratio of the channel and βc is its ‘critical’ value below which bars would not form. The theory leads to relationships for the maximum height and the maximum scour of bars which compare satisfactorily with the experimental data of various authors. Moreover the experimentally detected tendency of the bed perturbation to form diagonal fronts is qualitatively reproduced.

Type
Research Article
Copyright
© 1987 Cambridge University Press

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