Research On Application Of 3D Hydrodynamic, Sediment Transport Model With Non-Staggered Curvilinear Grid For Tidal Rivers

1. In this paper, a brief introduction of hydrodynamic, sediment transport model and its application in engineering projects are reported.2. The equations are derived using a tensor analysis of two-phase flow, and the background of basic equations and parameters in the numerical model are discussed.3. Based on Poission equation conversion, generated methods of curvilinear grids are presented.4. 2-D flow and sediment transport model with non-staggered curvilinear grids is presented. To prevent the pressure oscillation on non-staggered grids, an interpolation method called momentum interpolation is presented to evaluated the cell-face velocities. The contravariant velocity fluxes are used as the dependent variables in the paper. The discretization equations were sieved using the SIMPLE, SIMPLEC and SIMPLER algorithms. Suspended and bed load transport were simulated with a non-equilibrium method. The source treatments in sediment transport equations, suspended load carrying capacity of the non-uniform material and exchange of size-distribution of the bed material are presented.5. In order to verify and test the applicability of the model, "S" type open channel flow is simulated with this model, the agreement with measurements was generally good. The mathematical model was applied to serve the engineering projects. The different water levels and flow discharges in Nanjing river reach are calculated, bed scour and sedimentation in this engineering reach during one hydrologic year are verified . All results are in good agreement withfield measurements. River hydrodynamic conditions and bed scour and sedimentation were predicted using the numerical model under engineering design conditions.6. A 3-D flow and sediment model in curvilinear collocated grid is developed from 2-D model. In the horizontal x-y-plane, a boundary-fitted curvilinear co-ordinate system is adopted, while in the vertical direction, a o-co-ordinate transformation is used to represent free surface and bed topography. The total pressure is subdivided into the hydrostatic and residual hydrodynamic components. K-e turbulent flows model, non-staggered curvilinear grids, momentum interpolation, SIMPLEC and SIMPLER algorithms are used to solve the basic equations. Non-equilibrium sediment transport is applied in the model. The treatments of bed shear stress and the equilibrium concentration are presented.7. 3-D flow in "S" type channel bend is simulated. The suspended load model was tested for open channel flow situation under erosion and deposition, separately. The results for the numerical model are tested against available data. Good agreement is obtained.8. A simplified 3-D natural river flow and sediment transport model is developed based on hydrostatic pressure distribution. The model has been applied to investigate the 3-D flow and suspended-load transport in Nanjing river reach with two branches. Computed results show that the 3D distribution of flow velocities and suspended concentrations in two branches are in good agreement with field measurements. It shows that the simplified model is applicable and reliable.