Physically and numerically modelling turbulent flow in a patchy open channel

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Authors

Abstract

Traditionally, open channels have tended to be modelled assuming a difference in roughness between the bed and the walls of the channel. Whilst this is a reasonable starting point, the reality is much more complex with heterogeneous roughness elements (or roughness 'patches') regularly occurring on the bed of the channel. Given that the bed acts as a source of vorticity, a regular change in bed roughness causes varying levels of vorticity to be present at different cross sections. The 'new' vorticity, which occurs as a result of changes in bed roughness, interacts with the existing flow structures leading to a complex flow field which can either result in the manifestation of lateral or vertical shear layers depending on the magnitude of the relative roughness. This flow field has implications not only on the conveyance capacity of a channel but also on other parameters such as sediment transport. This paper presents results relating to a series of laboratory experiments investigating these phenomena. These results have been used to calibrate a numerical model. In the model f has been shown to have the most influence on the model followed by Γ, with λ being relatively unimportant and thus able to be modelled using the standard value without loss of accuracy.

Details

Original languageEnglish
Title of host publicationRiver Flow 2014:
Subtitle of host publicationProceedings of the International Conference on Fluvial Hydraulics
EditorsAnton J. Schleiss, Giovanni de Cesare, Mario J. Franca, Michael Pfister
Publication statusPublished - 2014
EventRiver Flow 2014:: 7th International Conference on Fluvial Hydraulics - Lausanne, Switzerland
Duration: 3 Sep 20145 Sep 2014
http://riverflow2014.epfl.ch/

Conference

ConferenceRiver Flow 2014:
CountrySwitzerland
CityLausanne
Period3/09/145/09/14
Internet address

Keywords

  • 2-D depth averaged modelling, Heterogeneous roughness, Turbulent structures