The three-dimensional movements of bed-load particles in an open channel with different grain diameters and different specific gravities under the conditions of different hydraulic gradient are measured by means of pa...The three-dimensional movements of bed-load particles in an open channel with different grain diameters and different specific gravities under the conditions of different hydraulic gradient are measured by means of particle tracking velocimetry(PTV)technique.The average movement characteristics of the particles are analyzed by statistics.The results show that the longitudinal average velocities of the particles neither agree with the law suggested by Einstein nor obey the law assumed by Bagnold.Einstein’s law is that the particle velocity is equal to 11.6 times of shear velocity,and the Bagnold’s law assumes the velocity equal to the difference between flow velocity at corresponding water depth and settling velocity of particle.Two formulas for determining the velocity of particle in the forms of expression given by Einstein and Bagnold are obtained according to the statistical results of experimental data,respectively.展开更多
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.50279013 and 50221903)the Science and Technology Innovation Foundation of Hohai University(No.2006406711).
文摘The three-dimensional movements of bed-load particles in an open channel with different grain diameters and different specific gravities under the conditions of different hydraulic gradient are measured by means of particle tracking velocimetry(PTV)technique.The average movement characteristics of the particles are analyzed by statistics.The results show that the longitudinal average velocities of the particles neither agree with the law suggested by Einstein nor obey the law assumed by Bagnold.Einstein’s law is that the particle velocity is equal to 11.6 times of shear velocity,and the Bagnold’s law assumes the velocity equal to the difference between flow velocity at corresponding water depth and settling velocity of particle.Two formulas for determining the velocity of particle in the forms of expression given by Einstein and Bagnold are obtained according to the statistical results of experimental data,respectively.
