scholarly journals A New Method for Measuring Flow Structure in the Benthic Boundary Layer Using an Acoustic Doppler Velocimeter

2008 ◽  
Vol 25 (5) ◽  
pp. 822-830 ◽  
Author(s):  
Tetsunori Inoue ◽  
Yoshiyuki Nakamura ◽  
Mikio Sayama
Keyword(s):  
Flow Structure ◽  
Precise Measurement ◽  
Shear Velocity ◽  
Turbulent Energy ◽  
Sediment Surface ◽  
Benthic Boundary Layer ◽  
Acoustic Doppler Velocimeter ◽  
Vertical Profiles ◽  
Advantages And Disadvantages ◽  
Turbulent Flow Structure

Abstract A new system for precise measurement of vertical profiles of mean and turbulent flow structure immediately above the sediment–water interface is introduced. This system has an acoustic Doppler velocimeter (ADV) attached to an elevation system to allow for the precise measurement of the vertical profiles of three-component velocities in the range of 0.1–27 cm above the sediment surface in the field. This system enables an onboard operator to accurately measure height and move the ADV vertically to any point. The system was applied to in situ measurements of velocity profiles immediately above the sediment. The shear velocity, Reynolds stress value, roughness height, turbulent kinetic energy, and dissipation rate of turbulent energy were calculated and compared with often-cited values. The results showed the same flow properties as those from laboratory experiments and literature values. The advantages and disadvantages of the system are discussed.

scholarly journals Turbulent flow structure at a 90-degree open channel confluence: Accounting for the distortion of the shear layer

2016 ◽  
Vol 12 ◽  
pp. 130-147 ◽  
Author(s):  
Saiyu Yuan ◽  
Hongwu Tang ◽  
Yang Xiao ◽  
Xuehan Qiu ◽  
Huiming Zhang ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Shear Layer ◽  
Flow Structure ◽  
Open Channel ◽  
Turbulent Flow Structure ◽  
Channel Confluence

Turbulent flow structure at a discordant river confluence: Asymmetric jet dynamics with implications for channel morphology

2017 ◽  
Vol 122 (6) ◽  
pp. 1278-1293 ◽  
Author(s):  
Alexander N. Sukhodolov ◽  
Julian Krick ◽  
Tatiana A. Sukhodolova ◽  
Zhengyang Cheng ◽  
Bruce L. Rhoads ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Flow Structure ◽  
Channel Morphology ◽  
River Confluence ◽  
Turbulent Flow Structure

Study on the Measuring Instruments and Strength Size Effect of the Surface Shape of Rigid Structure Plane

2011 ◽  
Vol 250-253 ◽  
pp. 2327-2332
Author(s):  
Feng Ji ◽  
Yu Chuan Shi
Keyword(s):  
Size Effect ◽  
Precise Measurement ◽  
Rock Sample ◽  
Surface Shape ◽  
Measuring Instruments ◽  
Rigid Structure ◽  
Advantages And Disadvantages ◽  
Structure Surface ◽  
Structure Plane ◽  
Working Efficiency

The surface shape of structure plane is closely related with its mechanics property. Precise measurement to the surface shape of structure plane is the basis of deformation mechanism and strength characteristics. On the basis of studying advantages and disadvantages of the measuring instrument, the author has developed a new kind of portable measuring instruments innovatively - Contact Punching Device which has improved open-air working efficiency greatly. Application results show that JRC obtained by the Contact Punching Device is very close to the actual JRC of surface shape of the structure plane. Then about size effect of rigid structure plane, got the following principle that the statistical variance of the undulating roughness of the structure surface decays gradually with length of the rock sample, and got the limiting length of the undulating roughness when the influence of shearing intensity of the structure is dispelled. Finally, which proved through the embodiment of different rock and different weathering rock, the result indicates this method can be applied to engineering.

Turbulent characteristics of flow in the vicinity of mid-channel braid bar

2020 ◽  
Author(s):  
Mohammad Amir Khan ◽  
Nayan Sharma ◽  
MANISH PANDEY ◽  
Mohd Obaid Qamar
Keyword(s):  
Turbulent Flow ◽  
Flow Structure ◽  
Turbulent Intensity ◽  
Flow Area ◽  
Fluvial Processes ◽  
Relative Dominance ◽  
Turbulent Characteristics ◽  
Turbulent Flow Structure ◽  
The Impact ◽  
Channel Bar

The impact of a mid-channel bar on the turbulent flow structure has been investigated in this research. A new Dominance Function S_(i,H) is proposed in this study as a measure of the relative dominance of ejection and sweep events in turbulent flow structure. Occurrence of the kolk-boil phenomenon is observed due to interaction of ejection and sweep events.. A new parameter Movement Ratio is formulated in this study which is found to faithfully reflect the fluvial processes of sedimentation and scouring on the channel bed.. Acceleration of flow is seen to occur at adjoining regions close to the upstream end of the bar. Due to the presence of the bar, the flow area in its proximity decreases which has caused increment in the velocity at sections located near the upstream end of the mid-channel bar. For model runs with bars, a distinct bulge in the turbulent intensity graph is observed.

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