COMPARISON BETWEEN PARTICLE-BASED AND SEMI-EMPIRICAL SEDIMENT TRANSPORT SIMULATIONS OF SCOUR AROUND A VERTICAL CYLIND

Sediment transport in rivers and coastal regions affects most structures built in or besides those kinds of marine environments. One of the effects of interest is scour around structures e.g. pipelines, see Ahmad et al. (2019), or jacket structure, see Ahmad et al. (2019a), and the resulting strain on the integrity of the structure around which the scour is occurring. As the length scales of sediment particles and structures are usually very different it is inherently difficult to simulate sediment transport. A wide range of formulations for sediment transport can therefore be found in literature. However, for practical applications where speed is important most of the initiation of sediment transport and the quantification of sediment loads are today calculated using continuum-based methods relying on empirical relationship. The same is true for the open-source computational fluid dynamics model REEF3D::CFD which predicts scour on small and large scale using a bed-load transport rate based on the shear stresses near the sediment bed and a convection-diffusion equation for the suspended load are used for the global transport. In addition, a sand slide algorithm using Exner’s formula is used to redistribute sediment on steep angles to account for local transport. The implementation of these processes is described in Ahmad (2018). We aim to simulate the physics involved in particle transport on a more detailed level and explore the use of a Lagrangian approach to describe the sediment particles instead of the original Eulerian approach currently available in REEF3D::CFD.