A three-dimensional numerical model is established to simulate the turbulent oscillatory boundary layer over a fixed and rough bed composed by randomly arrayed solid spheres based on the lattice Boltzmann method and t...A three-dimensional numerical model is established to simulate the turbulent oscillatory boundary layer over a fixed and rough bed composed by randomly arrayed solid spheres based on the lattice Boltzmann method and the large eddy simulation model.The equivalent roughness height,the location of the theoretical bed and the time variation of the friction velocity are investigated using the log-fit method.The time series of turbulent intensity and Reynolds stress are also investigated.The equivalent roughness height of cases with Reynolds numbers of 1×10^4–6×10^4 is approximately 2.81 d（grain size）.The time variation of the friction velocity in an oscillatory cycle exhibits sinusoidal-like behavior.The friction factor depends on the relative roughness in the rough turbulent regime,and the pattern of solid particles arrayed as the rough bed in the numerical simulations has no obvious effect on the friction factor.展开更多
The flow resistance factors of non-submerged rigid vegetation in open channels were analyzed. The formulas of drag coefficient CD and equivalent Manning＇s roughness coefficient na were derived by analyzing the force ...The flow resistance factors of non-submerged rigid vegetation in open channels were analyzed. The formulas of drag coefficient CD and equivalent Manning＇s roughness coefficient na were derived by analyzing the force of the flow of non-submerged rigid vegetation in open channel. The flow characteristics and mechanism of non-submerged rigid vegetation in open channel were studied through flume experiments.展开更多
基金The National Natural Science Foundation of China under contract No.51179122the Science Fund for Creative Research Groups of the National Natural Science Foundation of China under contract No.51621092
文摘A three-dimensional numerical model is established to simulate the turbulent oscillatory boundary layer over a fixed and rough bed composed by randomly arrayed solid spheres based on the lattice Boltzmann method and the large eddy simulation model.The equivalent roughness height,the location of the theoretical bed and the time variation of the friction velocity are investigated using the log-fit method.The time series of turbulent intensity and Reynolds stress are also investigated.The equivalent roughness height of cases with Reynolds numbers of 1×10^4–6×10^4 is approximately 2.81 d（grain size）.The time variation of the friction velocity in an oscillatory cycle exhibits sinusoidal-like behavior.The friction factor depends on the relative roughness in the rough turbulent regime,and the pattern of solid particles arrayed as the rough bed in the numerical simulations has no obvious effect on the friction factor.
文摘The flow resistance factors of non-submerged rigid vegetation in open channels were analyzed. The formulas of drag coefficient CD and equivalent Manning＇s roughness coefficient na were derived by analyzing the force of the flow of non-submerged rigid vegetation in open channel. The flow characteristics and mechanism of non-submerged rigid vegetation in open channel were studied through flume experiments.
