Lagrangian numerical modelling of rapid multiphase sediment transport.

Ehsan Jafari Nodoushan, Mohhana Tajnesaie, Ahmad Shakibaeini, Khosrow Hosseini

Wednesday 1 july 2015

12:15 - 12:30h at Mississippi (level 1)

Themes: (T) Sediment management and morphodynamics, (ST) Sediment transport mechanisms and modelling

Parallel session: 9A. Sediment - Transport

Rapid sediment motion, usually induced by highly erosive and transient flow in fluvial and coastal environments, is commonly encountered in many geo-morphological and engineering problems. Mobile-bed dam-break, submarine landslide, river bank failure and sediment flushing in reservoirs are only few examples of these problems. Accurate prediction the complexities involved in this water-sediment system (a multiphase dense granular flow system) is still a major challenge for many convention mesh-based models. Due to their ability to handle the high interfacial deformations and fragmentations, the mesh-free Lagrangian methods can provide a unique opportunity to deal with such complexities. This study aims to develop a multiphase mesh-free Lagrangian model, based on the Moving particle Semi-Implicit (MPS) formulation, for simulation of rapid transport of non-cohesive sediments. The sediment material is treated as a continuum (a non-Newtonian fluid) and visco-plastic rheological model is used to predict its local shear stress and effective viscosity. The model is validated for the cases of dry sediment slump and mobile-bed dam-break. The results of this study will not only evaluate the use mesh-free Lagrangian models for rapid sediment transport, but also provide a more thorough understanding of the complex mechanism and processes involved in rapid flow of sediments.