Flow modelling in gravel-bed rivers: rethinking the bottom boundary condition

Auteur(s) et Affiliation(s)



Description :
A key problem in computational fluid dynamics (CFD) modelling of gravel-bed rivers is the representation of multi-scale roughness, which spans the range from grain size, through bedforms, to channel topography. These different elements of roughness do not clearly map onto a model mesh and use of simple grain-scale roughness parameters may create numerical problems. This paper presents CFD simulations for 3 cases: a plane bed of fine gravel, a plane bed of fine gravel including large, widely-spaced pebble clusters, and a plane gravel bed with smaller, more frequent, protruding elements. Here, the spatially-averaged velocity and eddy viscosity are used to investigate the applicability of the model, compared with using the explicit high-resolution topography. The results show the ability of the model to capture the spatially-averaged flow field and, thus, illustrate its potential for representing flow processes in natural gravel-bed rivers. Finally, practical data requirements for implementing such a model for a field example are given.


Type de document :
Article de périodique

Source :
Earth surface processes and landforms, issn : 0197-9337, 2011, vol. 36, n°. 10, p. 1350-1366, nombre de pages : 17, Références bibliographiques : 1 p.

Date :
2011

Editeur :
Pays édition : Royaume-Uni, Chichester, Wiley