A 1-dimensional-two-layer transient drift-flux model for hydraulic transport pipelines
modelling and experiments of bed layer erosion and density wave amplification
E. de Hoog (TU Delft - Offshore and Dredging Engineering, Royal IHC)
Tjalie van der Voort (Royal IHC)
Arno Talmon (Deltares, TU Delft - Offshore and Dredging Engineering)
C Van Rhee (TU Delft - Offshore and Dredging Engineering)
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Abstract
Hydraulic transport pipelines in the dredging, mining and deep sea mining are designed using steady-state methods. However, these methods cannot predict density wave formation. Density waves form a risk for pipeline blockages, therefore there is a need to understand and preferably be able to model the process. The density waves studied in this research are caused by a stationary sediment deposit in the pipeline. This article explores the development of a new transient design model, based on 1-dimensional-two-layer Driftflux CFD. The two layers model the exchange of sediment between the turbulent suspension, and a stationary bed layer, and can therefore model density wave amplification. An empirical erosion-sedimentation closure relationship is applied to model the sediment exchange between the two layers, and is calibrated using experiments. The final model is also validated against a second experiment, specifically for density wave amplification. The experiments and the model show good agreement on the erosion of a stationary bed layer and the growth rate of a density wave and the amplitude of the density wave.