The grid drop concept is introduced and used to develop a micromechanism-based methodology for calculating watershed flow concentration. The flow path and distance traveled by a grid drop to the outlet of the watershe...The grid drop concept is introduced and used to develop a micromechanism-based methodology for calculating watershed flow concentration. The flow path and distance traveled by a grid drop to the outlet of the watershed are obtained using a digital elevation model （DEM）. Regarding the slope as an uneven carpet through which the grid drop passes, a formula for overland flow velocity differing from Manning＇s formula for stream flow as welt as Darcy＇s formula for pore flow is proposed. Compared with the commonly used unit hydrograph and isochronal methods, this new methodology has outstanding advantages in that it considers the influences of the slope velocity field and the heterogeneity of spatial distribution of rainfall on the flow concentration process, and includes only one parameter that needs to be calibrated. This method can also be effectively applied to the prediction of hydrologic processes in un-gauged basins.展开更多
Finite element method is based on element matrix, so regardless of whetherthe mesh is structured or unstructured, it Possesses an unified fashion of treatment. Finiteelement method in conjunction with unstructured gri...Finite element method is based on element matrix, so regardless of whetherthe mesh is structured or unstructured, it Possesses an unified fashion of treatment. Finiteelement method in conjunction with unstructured grid will improve the ability of numericalsimulation for complicated now field. In this paper, a 3D unstructured grid generationtechno1ogy is developed and the Euler equation on the unstructured mesh for real compli-cated aircraft configurations is solved by the finite e1ement method. Numerical results in-dicate that the method presented is reliable end efficient.展开更多
基金supported by the National Nature Science Foundation of China (Grant No. 50609005)the Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China (Grant No. 101075)
文摘The grid drop concept is introduced and used to develop a micromechanism-based methodology for calculating watershed flow concentration. The flow path and distance traveled by a grid drop to the outlet of the watershed are obtained using a digital elevation model （DEM）. Regarding the slope as an uneven carpet through which the grid drop passes, a formula for overland flow velocity differing from Manning＇s formula for stream flow as welt as Darcy＇s formula for pore flow is proposed. Compared with the commonly used unit hydrograph and isochronal methods, this new methodology has outstanding advantages in that it considers the influences of the slope velocity field and the heterogeneity of spatial distribution of rainfall on the flow concentration process, and includes only one parameter that needs to be calibrated. This method can also be effectively applied to the prediction of hydrologic processes in un-gauged basins.
文摘Finite element method is based on element matrix, so regardless of whetherthe mesh is structured or unstructured, it Possesses an unified fashion of treatment. Finiteelement method in conjunction with unstructured grid will improve the ability of numericalsimulation for complicated now field. In this paper, a 3D unstructured grid generationtechno1ogy is developed and the Euler equation on the unstructured mesh for real compli-cated aircraft configurations is solved by the finite e1ement method. Numerical results in-dicate that the method presented is reliable end efficient.
