Computational Fluid Dynamics–Based Evaluation and Verification of FISP Suspended Sediment Samplers

Abstract

Suspended sediment concentration is critical for many aspects of water resources management, such as sedimentation prevention in irrigation channels. Samplers from the Federal Interagency Sedimentation Project (FISP) are widely used for suspended sediment measurement. There is a need to evaluate their accuracy. This paper reports the use of a three-dimensional (3D) computational fluid dynamics (CFD) model to make such evaluation. Two selected depth-integrating samplers, D95 and D96, were studied, with the focus on the intrusion effect of the samplers. Suspended sediment transport was simulated to capture the entrainment, transport and deposition processes. The turbulence was simulated using a Reynolds-averaged Navier-Stokes (RANS) k-ω model. The samplers were placed at three different vertical locations in an open channel. The simulation results showed that the surrounding flow was disturbed by the sediment samplers. However, regardless of the vertical location of the samplers, they had a negligible effect on the sediment concentration at the inlet nozzle. The main reason is that the inlet nozzles of both samplers had enough protrusion upstream such that the intake was not affected by the sampler bodies. The results did not show significant vorticity at the inlet nozzle either, which in the past was suspected of imparting centrifugal force on sediment particles and thus having selective sampling efficiency depending on sediment sizes.