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
In this paper, a numerical computation method is developed for the computation of current field in the tidal zone, using the well-point method and ADI method. The computational results agree well with the general vari...In this paper, a numerical computation method is developed for the computation of current field in the tidal zone, using the well-point method and ADI method. The computational results agree well with the general variation of current field in the tidal zone.展开更多
This papaer presents an analytic formula for the locus of shock front of sphericalblast waves with back pressure. Meanwhile, it is shown that the wave velocity is inversely proportions to the area of shock wave in the...This papaer presents an analytic formula for the locus of shock front of sphericalblast waves with back pressure. Meanwhile, it is shown that the wave velocity is inversely proportions to the area of shock wave in the Lagrangian coordinate space. If shock wave ispropagating into the gas at rest, the wave velocity is also inversely propagating into the gasat rest, the wave velocity is also inversely proportional to the area of shock front in the Eulerian coordinate space. The results obtained are generally applicable and may be suited to thewave velocity of contracting spherical shock wave.展开更多
The formulae for average velocity of groundw-ater flow in a single fracturewere derived based on the characteristics of fracture properties and hydraulic methods. The resultsshow that the average velocity is proportio...The formulae for average velocity of groundw-ater flow in a single fracturewere derived based on the characteristics of fracture properties and hydraulic methods. The resultsshow that the average velocity is proportional to the square root of the hydraulic gradient. Inorder to verify the results, a laboratory model was established, and the experimental data wereanalyzed. Experimental results indicate that the relation between the average velocity and hydraulicgradient is nonlinear, and can he filled with power functions. And for both the unconfined andconfined flows, the value of the exponent of power functions are close to 0. 5. Thus the experimental results agree well with those from the theoretical analysis. By comparing the calculated andmeasured values of the average velocity under the same conditions, the formulae presented herein aremore effective than the traditional formula based on Darcy' s Law. These results provide theevidences of non-Dar-cy's flow in single fracture.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In this paper, a numerical computation method is developed for the computation of current field in the tidal zone, using the well-point method and ADI method. The computational results agree well with the general variation of current field in the tidal zone.
文摘This papaer presents an analytic formula for the locus of shock front of sphericalblast waves with back pressure. Meanwhile, it is shown that the wave velocity is inversely proportions to the area of shock wave in the Lagrangian coordinate space. If shock wave ispropagating into the gas at rest, the wave velocity is also inversely propagating into the gasat rest, the wave velocity is also inversely proportional to the area of shock front in the Eulerian coordinate space. The results obtained are generally applicable and may be suited to thewave velocity of contracting spherical shock wave.
基金Project supported by the National Natural Science Foundation of China.(Grant No:40202027)
文摘The formulae for average velocity of groundw-ater flow in a single fracturewere derived based on the characteristics of fracture properties and hydraulic methods. The resultsshow that the average velocity is proportional to the square root of the hydraulic gradient. Inorder to verify the results, a laboratory model was established, and the experimental data wereanalyzed. Experimental results indicate that the relation between the average velocity and hydraulicgradient is nonlinear, and can he filled with power functions. And for both the unconfined andconfined flows, the value of the exponent of power functions are close to 0. 5. Thus the experimental results agree well with those from the theoretical analysis. By comparing the calculated andmeasured values of the average velocity under the same conditions, the formulae presented herein aremore effective than the traditional formula based on Darcy' s Law. These results provide theevidences of non-Dar-cy's flow in single fracture.
