In this paper,according to the rule of unbalanced sediment transport and the analysis of field data,different water diversion schemes were theoretically studied,including the erosion and sedimentation trend as well as...In this paper,according to the rule of unbalanced sediment transport and the analysis of field data,different water diversion schemes were theoretically studied,including the erosion and sedimentation trend as well as their impacts on the environment of the middle and lower reaches of the Hanjiang River.The results showed that the 95×108m 3 water diversion scheme will cause less erosion and water level decrease than the 15×108m 3 water diversion scheme.Using a water diversion scheme of 95×108m 3,the decrease of water quantity can impact the river hydrodynamic regime substantially and the environments of the middle and lower reaches of the Hanjiang River will be greatly affected.It is therefore necessary to develop new water resources or build projects to meet the need of the environment and the needs for navigation.展开更多
A 3-D numerical formulation is proposed on the horizontal Cartesian, vertical sigma-coordinate grid for modeling non-hydrostatic pressure flee-surface flows. The pressure decomposition technique and 0 semi-implicit me...A 3-D numerical formulation is proposed on the horizontal Cartesian, vertical sigma-coordinate grid for modeling non-hydrostatic pressure flee-surface flows. The pressure decomposition technique and 0 semi-implicit method are used, with the solution procedure being split into two steps. First, with the implicit parts of non-hydrostatic pressures excluded, the provisional velocity field and free surface are obtained by solving a 2-D Poisson equation. Second, the theory of the differential operator is employed to derive the 3-D Poisson equation for non-hydrostatic pressures, which is solved to obtain the non-hydrostatic pressures and to update the provisional velocity field. When the non-orthogonal sigma-coordinate transformation is introduced, additional terms come into being, resulting in a 15-diagonal, diagonally dominant but unsymmetric linear system in the 3-D Poisson equation for non-hydrostatic pressures. The Biconjugate Gradient Stabilized （BiCGstab） method is used to solve the resulting 3-D unsymmetric linear system instead of the conjugate gradient method, which can only be used for symmetric, positive-definite linear systems. Three test cases are used for validations. The successful simulations of the small-amplitude wave, a supercritical flow over a ramp and a turbulent flow in the open channel indicate that the new model can simulate well non-hydrostatic flows, supercritical flows and turbulent flows.展开更多
文摘In this paper,according to the rule of unbalanced sediment transport and the analysis of field data,different water diversion schemes were theoretically studied,including the erosion and sedimentation trend as well as their impacts on the environment of the middle and lower reaches of the Hanjiang River.The results showed that the 95×108m 3 water diversion scheme will cause less erosion and water level decrease than the 15×108m 3 water diversion scheme.Using a water diversion scheme of 95×108m 3,the decrease of water quantity can impact the river hydrodynamic regime substantially and the environments of the middle and lower reaches of the Hanjiang River will be greatly affected.It is therefore necessary to develop new water resources or build projects to meet the need of the environment and the needs for navigation.
基金Project supported by the National Key Basic Research Program of China (973 Program, Grant No. 2007CB714100)the Key Project of National Natural Science Foundation of China (Grant No. 51039003)supported by the Yangtze River Scientific Research Institute project (Grant No. CKSQ2010075)
文摘A 3-D numerical formulation is proposed on the horizontal Cartesian, vertical sigma-coordinate grid for modeling non-hydrostatic pressure flee-surface flows. The pressure decomposition technique and 0 semi-implicit method are used, with the solution procedure being split into two steps. First, with the implicit parts of non-hydrostatic pressures excluded, the provisional velocity field and free surface are obtained by solving a 2-D Poisson equation. Second, the theory of the differential operator is employed to derive the 3-D Poisson equation for non-hydrostatic pressures, which is solved to obtain the non-hydrostatic pressures and to update the provisional velocity field. When the non-orthogonal sigma-coordinate transformation is introduced, additional terms come into being, resulting in a 15-diagonal, diagonally dominant but unsymmetric linear system in the 3-D Poisson equation for non-hydrostatic pressures. The Biconjugate Gradient Stabilized （BiCGstab） method is used to solve the resulting 3-D unsymmetric linear system instead of the conjugate gradient method, which can only be used for symmetric, positive-definite linear systems. Three test cases are used for validations. The successful simulations of the small-amplitude wave, a supercritical flow over a ramp and a turbulent flow in the open channel indicate that the new model can simulate well non-hydrostatic flows, supercritical flows and turbulent flows.
