1DH modeling of transport and sedimentation inside a hopper of a trailing suction dredger
CEDA Dredging Days 2017 - Sustainable Dredging - Continued Benefits
Boone J., de Nijs M.A.J
Abstract: This paper describes the development of a novel transient one-dimensional horizontal simulation model that predicts the transport and sedimentation of sand along a hopper of a trailing suction dredger. This model includes an external current model and an internal current model. These models solve cross-section averaged mass and momentum equations to predict the transport by barotropic and baroclinic currents. These models are mutually coupled by vertical exchange processes. Relevant vertical physical processes are modelled using closure relations for hindered settling, entrainment, erosion and continuity-based vertical transport of water and sediment. Both the external current model and the internal current model are dynamically coupled with the sediment bed through deposition and erosion.
We provide a practical simulation tool that balances the need of sufficient predictive capability through simulation of time and along hopper variation of model quantities with the requirement of low computational effort and complexity compared to transient two-dimensional vertical or three-dimensional models through the use of closure assumptions to model vertical processes.
The hydrodynamic model is verified against a number of idealised analytical solutions. These tests demonstrate that the discretised model is mass and momentum conservative and that it can cope with drying and flooding phenomena. The model is validated against laboratory and prototype measurements. We show that our model can predict the total cumulative overflow losses on laboratory and prototype scale well at low user complexity level and at low computational time. Consequently, Van Oord has acquired the knowledge and tool to predict the overflow of sediments and the along hopper sediment bed layer distribution, and to optimize equipment and working strategies.
Key words: hopper sedimentation, gravity currents, cross-section averaged, overflow losses