GU Fangzheng, ZHANG Huilan, WANG Linghan, et al. The Influence of Gradient Surface Roughness on the Hydrodynamic Characteristics of Overland Flow Based on PIV[J]. 2023, 37(6): 18-24.
DOI:
GU Fangzheng, ZHANG Huilan, WANG Linghan, et al. The Influence of Gradient Surface Roughness on the Hydrodynamic Characteristics of Overland Flow Based on PIV[J]. 2023, 37(6): 18-24. DOI: 10.13870/j.cnki.stbcxb.2023.06.003.
The Influence of Gradient Surface Roughness on the Hydrodynamic Characteristics of Overland Flow Based on PIV
Roughness is a key factor affecting the hydrodynamic characteristics of overland flow. In order to explore the hydraulic characteristics of overland flow under the influence of gradient roughness
using particle image velocimetry (PIV) to observe and analyze the velocity profile
turbulence intensity
Reynolds stress and wall shear stress of the overland flow under the three groups of flow rates. The results showed that: (1) The flow velocity decreased with the increase of roughness; the logarithmic formula of velocity distribution was obtained by fitting the dimensionless velocity. The increase of roughness was inversely proportional to the fitting constant A and proportional to the integral coefficient B. (2) The trend of streamwise turbulence intensity of gradient surface roughness was similar to that of smooth bed slope. The streamwise turbulence intensity decreased with the increase of relative water depth. With the increase of roughness
there was a nonsignificant difference in the intensity of streamwise turbulence. The turbulence intensity under the gradient rough bed was consistent with the Nezu empirical formula
and the flow rate was proportional to the empirical coefficient. (3) Under different flow rates
the Reynolds stress distribution of the graded rough bed was similar to that of the smooth bed. Under the influence of roughness
the maximum Reynolds stress appeared at y/H = 0.2~0.4. With the increase of roughness
the wall shear stress increased gradually. The synthesis showed that the method of increasing PIV resolution could be applied to the study of hydraulic characteristics of overland flow. Exploring the influence of gradient roughness on slope flow and exploring the hydrodynamic characteristics of slope flow provide new ideas for theoretical research of soil and water conservation.
Zhao C H, Gao J E, Huang Y F, et al. Effects of vegetation stems on hydraulics of overland flow under varying water discharges[J].Land Degradation and Development,2016,27(3):748-757.
Henao-Garcia S, Xiao C N, Senocak I. Investigation of oscillations in katabatic Prandtl slope flows[J].Quarterly Journal of the Royal Meteorological Society,2023,149(750):247-261.
Shin S S, Park S D, Sim Y J, et al. Hydraulic conditions of incipient rill by raindrop-induced overland flow on steep slopes of sandy soil[J].Water,2023,15(3):e502.
Yang P P, Zhang H L, Wang Y Q, et al. Overland flow velocities measured using a high-resolution particle image velocimetry system[J].Journal of Hydrology,2020,590:e125225.
Sadeque M A, Rajaratnam N, Loewen M R. Effects of bed roughness on flow around bed-mounted cylinders in open channels[J].Journal of Engineering Mechanics,2009,135(2):100-110.
Nezu I. Open-channel flow turbulence and its research prospect in the 21st century[J].Journal of Hydraulic Engineering,2005,131(4):229-246.
Keulegan G H. Laws of turbulent flow in open channels[J].Journal of Research of the National Bureau of Standards,1938,21(6):e707.
Subhasish Dey, Vijit Rathore, Nadia Penna, et al. Hydrodynamics of flow over a gradually varied bed roughness[J]. Physics of Fluid,2021,33(12):e125112.
Joel Sundstrom L R, Cervantes M J. Characteristics of the wall shear stress in pulsating wall-bounded turbulent flows[J].Experimental Thermal and Fluid Science,2018,96:257-265.