A comparison of different slurry transport models for sands & gravels

In dredging, sand and gravel are often transported through pipelines mixed with water. In order to determine the pumping power required, but also predict whether there will be a bed or not, the resistance (hydraulic gradient) and the Limit Deposit Velocity (LDV) have to be determined. The transport process is always an interaction between the pump and the pipeline resistance of the mixture transported. An important parameter is the LDV, the line speed above which there is no fixed or sliding bed. There are many models in literature to determine the resistance, expressed as the hydraulic gradient, and the LDV, but which models are best suited for the case considered. For the pipeline resistance models, the following categories can be distinguished: 2LM or 3LM sliding bed model, concentration distribution based models, semi-empirical heterogeneous flow regime models and homogeneous flow regime models. For the LDV about 25 models are compared, where most models are semi-empirical. The paper will give an overview of the most used models and show methods to compare these models and make a choice of the best suited model, the Delft Head Loss & Limit Deposit Velocity (DHLLDV) Framework.