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Flow structure and shear stress in the presence of both ice cover on water surface and leafless vegetation in channel bed

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Journal of Hydrodynamics 2024年第2期36卷 340-354页

作者： Mahboubeh Barahimi jueyi sui School of Engineering University of Northern British ColumbiaPrince GeorgeCanada

This study aimed to investigate the previously unexplored effects of ice cover and submerged vegetation on flow *** were undertaken under both open channel and ice-covered flow *** bed material consisted of three non-uniform *** findings revealed that when vegetation patches were present on the bed and an ice cover was present,the velocity profiles exhibited a distinctive pattern with two peak *** kinetic energy(TKE)also exhibited two peaks,one above the vegetation bending height and another at the sheath section,with a decreasing trend towards the ice ***,quadrant analysis showed that when the flow surface is covered by an ice cover,the contributions of inward and outward events increased compared with those observed in an open channel *** most cases,these contributions surpassed the sweep and ejection *** findings enhance our understanding of vegetation’s response to diverse surface conditions and have practical implications for river management and environmental engineering.

关键词： Ice cover vegetation flow structure Reynolds shear stress turbulent kinetic energy(TKE) quadrant analysis

Revisit submergence of ice blocks in front of ice cover–an experimental study

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Journal of Hydrodynamics 2018年第2期30卷 336-344页

作者： Jun Wang Yi-fan Wu jueyi sui College of Civil and Hydraulic Engineering Hefei University of Technology Hefei 230009 China Environmental Sciences and Engineoring Program University of Northern British Columbia Prince George BC Canada

The present paper studies the stabilities of ice blocks in front of an ice cover based on experiments carried out in laboratory by using four types of ice blocks with different dimensions. The forces acting on the ice blocks in front of the ice cover are analyzed. The critical criteria for the entrainment of ice blocks in front of the ice cover are established by considering the drag force caused by the flowing water, the collision force, and the hydraulic pressure force. Formula for determining whether or not an ice block will be entrained under the ice cover is derived. All three dimensions of the ice block are considered in the proposed formula. The velocities calculated by using the developed formula are compared with those of calculated by other formulas proposed by other researchers, as well as the measured flow velocities for the entrainment of ice blocks in laboratory. The fitting values obtained by using the derived formula agree well with the experimental results.

关键词： Criteria for entrainment ice Froude number ice block ice cover dimension of ice block

Numerical simulation of mechanical breakup of river ice-cover

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Journal of Hydrodynamics 2013年第3期25卷 415-421页

作者：王军何亮陈胖胖 sui jueyi School of Civil Engineering Hefei University of Technology Environmental Engineering Program University of Northern British Columbia Prince George Bristish ColumbiaCanada

Ice jams and ice dams in rivers will cause significant rises of water levels. Under extreme conditions, the ice flooding during winter or early spring may occur. In this paper, by considering the fluid-solid coupling effect caused by the water and the ice cover, the mechanisms of the mechanical breakup of the river ice cover are studied. A formula is obtained for determining whether or not the mechanical breakup process would happen under the hydraulic pressure of the flow. Combined with the hydraulic model under the ice covered flow, a numerical model is built and the interaction between the discharge, the hydraulic pressure under the ice cover and the date for the mechanical breakup of the river ice cover is simulated. The simulated results of the dates for the mecha- nical breakup of the river ice cover agree very well with the field observations of the breakups of the river ice cover in the Hequ Reach of the Yellow River. Therefore, the numerical model might serve as a good preliminary step in studying the breakup of the river ice-cover, evidencing many important parameters that affect the ice-cover process,

关键词： criterion for breakup fluid-solid coupling effect Hequ Reach of the Yellow River ice cover mechanical breakup,numerical model

Effect of vegetated-banks on local scour around a wing-wall abutment with circular edges

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Journal of Hydrodynamics 2014年第3期26卷 447-457页

作者： AFZALIMEHR Hossein BAKHSHI Somayeh GALLICHAND Jacques sui jueyi Department of Water Engineering Isfahan University of Technology Isfahan Iran Department Des Sols Et De Génie Agroalimentaire Pavillon Paul-Comtois Université Laval St-Foy QC Canada Environmental Engineering program University of Northern British Colombia Prince George BC Canada

Failure of bridges due to local scour in the vicinity of bridge abutments is a common occurrence. In this study, experiments under two different channel conditions were conducted to assess the impacts of vegetation on channel banks on local scour around a wing-wall abutment with circular edges. Some experiments were conducted in channel with vegetation on channel banks, and other experiments in channel without vegetation on channel bank. The flow velocity and Reynolds stress distributions in scour holes around a wing-wall abutment with circular edges were compared under these 2 different channel conditions. Results reveal that the vegetated-banks can reduce the time for achieving the equilibrium condition from 17 h to 9 h. Also, vegetated-bank channels can result in a significant decrease in the maximum scour depth from 0.084 m（for bare channel bank） to 0.00032 m. Additionally, around the abutment, vegetated-banks play a significant role in diminishing the Reynolds stress（RS） near the bed and removing negative values in RS distribution by weakening unfavorable pressure gradient and down-flow in the upstream of abutment.

关键词： local scour vegetated-banks wing-wall abutment circular edges Reynolds stress(RS)

Impacts of bridge piers on water level during ice jammed period in bend channel——An experimental study

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Journal of Hydrodynamics 2018年第1期30卷 160-168页

作者：王军李淑祎陈胖胖汪涛 jueyi sui College of Civil and Hydraulic Engineering Hefei University of Technology Environmental Sciences and Engineering Program University of Northern British Columbia

Experiments are carried out in an ＂S-shaped＂ flume in the laboratory under both open flow and ice-jammed conditions to study the impacts of bridge piers in a bend channel on the variation of the water level. The variations of the water level under the ice jammed condition with bridge piers are compared to those without bridge piers in an 180° bend channel. Results indicate that the bridge piers in the S-shaped channel have obvious impacts on the ice accumulation and the water level. The increment of the water level with the presence of the bridge piers is less than that without the bridge piers in the channel. Different arrangements of the bridge piers result in different increments of the water level. When one bridge pier is installed in the straight section of the channel（between 2 bends） and another one at the bend apex（for a convex bank）, the increment of the water level during the equilibrium ice jammed period is between that with a single bridge pier located in the straight section of the bend channel and that with a single bridge pier located at the bend apex. It is also shown that the increment of the water level during the equilibrium ice jammed period increases with the increase of the average thickness of the ice jams.

关键词： Ice jam bend channel bridge pier increment of water level

Characteristics of turbulent flow in 3-D pools in the presence of submerged rigid vegetation in channel bed

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Journal of Hydrodynamics 2024年第1期36卷 158-169页

作者： Kourosh Nosrati Hossein Afzalimehr jueyi sui Hamid Reza Reisifar Natural Disasters Prevention Research Center Faculty of Civil EngineeringIran University of Science and TechnologyTehranIran School of Engineering University of Northern British ColumbiaPrince GeorgeCanada

In this study,the interaction between 3-D bedforms and submerged rigid vegetation has been *** laboratory experiments were conducted to study the distribution of flow velocity,Reynolds shear stress,turbulent kinetic energy,and skewness coefficients for a constant density of *** showed that the velocity profile in the pool section deviates from those in the upstream section of the *** has been found that the dip parameter varied between 0.6H and 0.9H depending on various factors including bed roughness,vegetation distribution,and pool entrance/exit ***,scattered vegetation in the pool and differences in slopes created non-uniform flow ***,in the wake region behind each vegetated element,flow velocity reduced significantly,and small-scale eddies are formed,causing increased *** decreasing the entrance slope and bed roughness,relatively uniform flow and weaker turbulence was resulted,but the random distribution of vegetated elements counteracted this balance and intensified *** the decrease in the pool entrance slope,the contribution of sweep event decreased and the contribution of ejection event increased.

关键词： Submerged rigid vegetation 3-D pool Reynolds shear stress skewness coefficients

Local scour around two side-by-side cylindrical bridge piers under ice-covered conditions

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International Journal of Sediment Research 2019年第4期34卷 355-367页

作者： Mohammad reza Namaee jueyi sui Environmental Engineering Program University of Northern British Columbia

In the current study, 108 flume experiments with non-uniform, cohesionless sediments have been done to investigate the local scour process around four pairs of side-by-side bridge piers under both open channel and ice-covered flow conditions. Similar to local scour around bridge piers under open channel conditions and a single bridge pier, it was observed in the experiments that the maximum scour depth always occurred at the upstream face of the pier under ice-covered conditions. Further, the smaller the pier size and the greater the spacing distance between the bridge piers, the weaker the horseshoe vortices around the bridge piers, and, thus, the shallower the scour holes around them. Finally, empirical equations were developed to estimate the maximum scour depth around two side-by-side bridge piers under both open channel and ice-covered flow conditions.

关键词： Bridge pier Local scour Maximum scour depth Non-uniform sediment Roughness of cover Scour pattern

Impacts of vegetation over bedforms on flow characteristics in gravel-bed rivers

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Journal of Hydrodynamics 2019年第5期31卷 986-998页

作者： Hossein Afzalimehr Mohammad Reza Maddahi jueyi sui Majid Rahimpour Department of Civil Engineering Iran University of Science and TechnologyTehranIran Department of Water Engineering Shahid Bahonar University of KermanKermanIran Environmental Engineering Program University of Northern British ColumbiaCanada

In the present study,among six gravel-bed river reaches,two natural gravel-bed river reaches with approximately similar bedforms and flow conditions have been found,one river reach with vegetation on bedforms and the other without vegetation on *** on field measurements,the impacts of vegetation over bedforms on flow characteristics have been *** velocity,Reynolds stress and turbulence intensity distributions over bedforms with vegetation have been compared with those over gravel bedforms without *** using the quadrant analysis,the dominant events of turbulent flow structures have been assessed for flows over gravel bedforms with vegetation and without *** show that the effect of vegetation enhances the anisotropy in turbulence and generates strong secondary currents,which lead to the occurrence of dip phenomenon at the stoss section and the crest of vegetated *** change of bed roughness from gravel bed to vegetated bed causes a development of a new boundary *** resulted in the different shape of velocity distributions over bedforms with vegetation from those over bedforms without vegetation,which can affect the lives of aquatic *** shear stress at downstream section of gravel bedform without vegetation is much higher than that of vegetated bedform,which shows that the erosion takes place from downstream of vegetated bedforms,while in the bare beds;the deposition is at downstream of *** is found that the presence of vegetation causes a chaotic distribution pattern of Reynolds shear stress,while it has more orderly pattern at the downstream section of gravel bedform without ***,the distribution of turbulence intensity in the lee side of vegetated bedform has a concave shape and in the stoss section,turbulence is generated in ejections and sweeps near the vegetation *** findings are significant to the practice of river ecological restoration.

关键词： Bedform Reynolds shear stress distribution turbulence intensity vegetation velocity profiles

Impacts of ice cover on local scour around semi-circular bridge abutment

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Journal of Hydrodynamics 2014年第1期26卷 10-18页

作者： WU Peng HIRSHFIELD Faye sui jueyi 王军陈胖胖 Environmental Engineering University of Northern British Columbia School of Civil Engineering Hefei University of Technology

The presence of ice cover in winter can significantly change the flow field around bridge abutments, which can also cause a different local scour pattern. To investigate the impacts of ice cover, results from a recent flume experiments were presented. Smooth and rough ice covers were created to investigate the impacts of ice cover roughness on the scour geometry around the semi-circular abutment. Three bed materials were used, with 50D s of 0.58 mm, 0.50 mm, 0.47 mm respectively. Scour volume and scour area were calculated. It was found that the maximum scour depth was located 75o inclined to the flume wall. Under rough ice cover, the scour area and scour depth were the largest. An empirical equation on the maximum scour depth was also developed.

关键词： ice cover local scour semi-circular abutment maximum scour depth scour pattern