Modeling Sediment Transport in Turbulent Open Channel Flows

Jungsun Oh, Sung-Uk Choi

Wednesday 1 july 2015

12:42 - 12:45h at Mississippi (level 1)

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

Parallel session: Poster pitches: 8A. Sediment - Erosion

The most commonly used method of simulating flows and transport of other phases in a flow is averaged equations for conservation of mass, momentum, and energy for each phase, and a set of equations for the transfer of mass, momentum, and energy between phases. The method provides quite reasonable results on the average trend of flow and sediment transport. However, the method is not sufficient to perform analysis of sediment dynamics. Sediment particles are the discrete phase that can exchange mass, momentum and energy with the fluid phase. In this study, therefore, we adopt a hybrid approach to modeling sediment transport so that we can analyze the detailed patterns of sediment particles in open channel flows. The fluid phase is considered a continuum by solving the Reynolds-averaged Navier-Stokes equations, whereas the dispersed solid phase is solved by numerically integrating the equations of motion for the dispersed phase, i.e. tracking a large number of particles through the calculated flow field. The non-linear k-_ model is chosen as a fluid-dynamic model in that the non-linear k-_ model is capable of simulating the generation of secondary flows by taking account of the anisotropic turbulent behavior. A stochastic particle tracking model is chosen to simulate particles in a flow. As a result, combining a Lagrangian approach with a fluid-dynamic model can yield very accurate solutions for sediment transport. In particular, the proposed model enables us to analyze the patterns related to sediment dynamics. Near-wall treatment affect the accuracy of simulation results_flow and sediment dynamics.