CGRG Bibliography of Canadian Geomorphology
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Author : Biron, P.; Han, S.; and Ramamurthy, A.S.
Date : 2001.
Title : Three-dimensional numerical modelling of complex natural flows: advances and challenges.
Publication : The Canadian Association of Geographers/l'association Canadienne des Géographes. 2001 Annual Meeting. 50th Anniversary of the CAG Jointly Organised by McGill University, Concordia University and Université de Montréal Tuesday May 29 – Sunday June 3, 2001.
Issue :
Page(s) :
Abstract
Three-dimensional numerical modelling has been used recently to investigate river processes in meanders or at confluences. Although promising results were obtained, there remain many difficulties associated with modelling complex situations. These can occur due to sharp changes in planform geometry or in bed topography, as is the case at river confluences. The objective of this study is to investigate the flow structure at an asymmetrical confluence (Bayonne-Berthier, Québec) for low and high flow conditions using 3D numerical modelling. Both tributaries are 8 m wide and the junction angle is around 55°. The computational mesh was created from detailed topographic surveys (1.15 points/m 2 ). Results show that the impact of the mesh geometry on the simulations is considerable. When the angle between individual cells in the mesh decreases due to the curvature of the tributary channel, numerical instabilities tend to propagate to relatively large areas of the computational domain. Furthermore, bank irregularities may create local instabilities. These problems were solved using a grid-generator software. The simulated 3D flow field and turbulent kinetic energy pattern corresponded well to turbulent velocity measurements taken at this site. Simulations clearly showed the distortion of the mixing plane due to the depth difference between the tributary and main channel.
Bibliography of Canadian Geomorphology