Physical and coupled fully three-dimensional numerical modeling of pressurized bottom outlet flushing processes in reservoirs

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Résumé

Sediment deposition in reservoirs is an important research topic in engineering practice. Reservoir
sedimentation has the potential to affect flood levels, drainage for agricultural land, pump station and
hydropower operation as well as navigation. This paper describes the development of a coupled fully
three-dimensional (3D) numerical model for the prediction of the local sediment flushing scour
upstream of the bottom outlet. The presented numerical model solves the Navier-Stokes equations in
conjunction with the k- ɛ turbulence model which includes both sediment transport and hydrodynamic
parameters. The proposed coupled fully 3D numerical model is used to simulate experimental tests based
on non-cohesive sediment. The geometric features of the scour hole (temporal and spatial hole development)
upstream of the bottom outlet were reasonably well predicted compared to the experimental
data. Furthermore, the velocity field upstream of the bottom outlet was in good agreement with measurements.
The proposed numerical model for bottom outlet flushing was, therefore, validated because
of its ability to accurately predict the scour hole development during the flushing process. The proposed
numerical model can be considered reliable provided that the model is correctly calibrated and set up to
reflect the conditions of a particular case study.

Mots-clés

Bottom outlet Coupled flow/sediment model Sediment flushing 3D numerical model Packed bed Reservoir