scholarly journals Erosion Resistance Performance of Surface-Reinforced Levees Using Novel Biopolymers Investigated via Real-Scale Overtopping Experiments

Water ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 2482
Author(s):  
Woochul Kang ◽  
Dongwoo Ko ◽  
Joongu Kang
Keyword(s):  
Three Dimensional ◽  
Acoustic Doppler Current Profiler ◽  
Economic Losses ◽  
Delay Effect ◽  
Current Profiler ◽  
New Material ◽  
Research Findings ◽  
Cloud Modeling ◽  
Scale Experiment ◽  
Real Scale

This study evaluates a novel biopolymer-based material reinforcement method. A real-scale experiment minimizing flood disasters and economic losses incurred by the collapse of river levees due to overtopping was conducted. At the Andong River Experiment Center, lateral overflow was reproduced to induce levee collapse using sand, reinforced novel materials, and vegetation levees represented as cases 1, 2, and 3, respectively. The flow in the upstream and downstream areas was measured, and fluctuations in the lateral overflow discharge were calculated using an acoustic Doppler current profiler. To quantitatively verify the performance of this method, the collapse delay effect based on the surface loss rate of the levee slope was analyzed using image pixel analysis and three-dimensional point cloud modeling. Comparing the collapse delay effect of the new-material levee with that of the non-reinforced levees, we found a time delay of approximately 2.7–7 times from the occurrence of overtopping via the lateral flow to the end of the test. These results indicate that we can secure time for emergency repairs and operations by reinforcing the levee surface using the material proposed in this study. These research findings are expected to provide the basis for the proper design and construction of river levees.

Numerical modeling study of impact of a large sediment capping facility on local industrial cooling water temperature

2010 ◽  
Vol 37 (10) ◽  
pp. 1289-1302 ◽  
Author(s):  
Cheng He
Keyword(s):  
Water Temperature ◽  
Thermal Structure ◽  
Three Dimensional ◽  
Cooling Water ◽  
Acoustic Doppler Current Profiler ◽  
Vertical Temperature Profile ◽  
Buoyant Force ◽  
Cooling Water Temperature ◽  
Current Profiler ◽  
Long Channel

This study assesses the potential increase in the intake cooling water temperatures if both the local industrial intake water and outfall cooling waters are trapped in the same narrow long channel. A three-dimensional (3D) hydrodynamic model was used to quantitatively investigate water temperature structures in the channel. The model was verified in a previous hydrodynamic study at the same location using vertical current profiles measured by an acoustic Doppler current profiler (ADCP) and further verified in this study with the measured vertical temperature profile. Several scenarios were investigated under various wind and geometrical conditions. The simulated results revealed that because of the strong buoyant force induced by water temperature differences the trapped hot outfall water would not be directly retaken by the intake located about 70 m away from the outlet and 6 m below the surface. The thermal structure in the channel eventually reached an equilibrium stage due to additional fresh bay water and heat loss through various heat-transfer mechanisms from the air–water interface. The results of this modelling study can be extended to solve other similar environmental and civil engineering problems.

scholarly journals Direct Observations of Along-Isopycnal Upwelling and Diapycnal Velocity at a Shelfbreak Front*

2004 ◽  
Vol 34 (3) ◽  
pp. 543-565 ◽  
Author(s):  
John A. Barth ◽  
Dave Hebert ◽  
Andrew C. Dale ◽  
David S. Ullman
Keyword(s):  
Three Dimensional ◽  
Internal Tide ◽  
Acoustic Doppler Current Profiler ◽  
Density Field ◽  
Strong Mixing ◽  
Optical Fields ◽  
Direct Observations ◽  
Current Profiler ◽  
Southern Flank ◽  
Coastal Front

Abstract By mapping the three-dimensional density field while simultaneously tracking a subsurface, isopycnal float, direct observations of upwelling along a shelfbreak front were made on the southern flank of Georges Bank. The thermohaline and bio-optical fields were mapped using a towed undulating vehicle, and horizontal velocity was measured with a shipboard acoustic Doppler current profiler. A subsurface isopycnal float capable of measuring diapycnal flow past the float was acoustically tracked from the ship. The float was released near the foot of the shelfbreak front (95–100-m isobath) and moved 15 km seaward as it rose from 80 to 50 m along the sloping frontal isopycnals over a 2-day deployment. The float's average westward velocity was 0.09 m s−1, while a drifter drogued at 15 m released at the same location moved westward essentially alongfront at 0.18 m s−1. The float measured strong downward vertical velocities (in excess of 0.02 m s−1) associated with propagation of internal tidal solibores in the onbank direction from their formation near the shelf break. The float measured large upward vertical velocities (in excess of 0.001 m s−1 ≃ 100 m day−1) as the pycnocline rebounded adiabatically after the passage of the internal tide solibore. The directly measured mean along-isopycnal vertical velocity was 17.5 m day−1. Intense mixing events lasting up to 2 hours were observed in the shelfbreak front at the boundary between cold, fresh shelf water and warm, salty slope water. Diapycnal velocities of up to 3 × 10−3 m s−1 were measured, implying a diapycnal thermal diffusivity as large as 10−2 m2 s−1, indicative of strong mixing events in this coastal front.

scholarly journals Three Dimensional Numerical Simulations of Internal Tides in the Angolan Upwelling Region

2021 ◽  
Author(s):  
Zhi Zeng ◽  
Peter Brandt ◽  
Kevin Lamb ◽  
Richard Greatbatch ◽  
Marcus Dengler ◽  
...  
Keyword(s):  
Seasonal Variations ◽  
Three Dimensional ◽  
Austral Summer ◽  
Acoustic Doppler Current Profiler ◽  
Ocean Model ◽  
Internal Tides ◽  
Austral Winter ◽  
Biological Productivity ◽  
Local Wind ◽  
Current Profiler

<p><span>In austral winter, biological productivity at the Angolan shelf reaches its maximum. The alongshore winds, however, reach their seasonal minimum suggesting that processes other than local wind-driven upwelling contribute to near-coastal cooling and upward nutrient supply, one possibility being mixing induced by internal tides (ITs). Here, we apply a three-dimensional ocean model to simulate the generation, propagation and dissipation of ITs at the Angolan continental slope and shelf. Model results are validated against moored acoustic Doppler current profiler and other observations. Simulated ITs are mainly generated in regions with a critical/supercritical slope typically between the 200- and 500-m isobaths. Mixing induced by ITs is found to be strongest close to the coast and gradually decreases offshore thereby contributing to the establishment of cross-shore temperature gradients. The available seasonal coverage of hydrographic data is used to design simulations to investigate the influence of seasonally varying stratification characterized by low stratification in austral winter and high stratification in austral summer. The results show that IT characteristics, such as their wavelengths, sea surface convergence patterns and baroclinic structure, have substantial seasonal variations and additionally strong spatial inhomogeneities. However, seasonal variations in the spatially-averaged generation, onshore flux and dissipation of IT energy are weak. By evaluating the change of potential energy, it is shown, nevertheless, that mixing due to ITs is more effective during austral winter. We argue this is because the weaker background stratification in austral winter than in austral summer acts as a preconditioning for IT mixing.</span></p>

scholarly journals Acoustic Doppler Current Profiler measurements near a weir with fish pass: assessing solutions to compass errors, spatial data referencing and spatial flow heterogeneity

2015 ◽  
Vol 47 (3) ◽  
pp. 591-605 ◽  
Author(s):  
Thomas Kriechbaumer ◽  
Kim Blackburn ◽  
Nick Everard ◽  
Monica Rivas Casado
Keyword(s):  
Spatial Data ◽  
Three Dimensional ◽  
Acoustic Doppler Current Profiler ◽  
Processing Technique ◽  
Engineering Structures ◽  
Integration Algorithm ◽  
Flow Heterogeneity ◽  
Fish Pass ◽  
Flow Maps ◽  
Current Profiler

There has been an increasing interest in the use of Acoustic Doppler Current Profilers (ADCPs) to characterise the hydraulic conditions near river engineering structures such as dams, fish passes and groins, as part of ecological and hydromorphological assessments. However, such ADCP applications can be limited by compass errors, obstructed view to navigation satellites, frequent loss of bottom tracking and spatially heterogeneous flow leading to erroneous water velocity measurements. This study addresses these limitations by (i) developing a heading sensor integration algorithm that corrects compass errors from magnetic interference, (ii) testing a Total Station based technique for spatial ADCP data referencing and (iii) evaluating a recently proposed data processing technique that reduces bias from spatial flow heterogeneity. The integration of these techniques on a radio control ADCP platform is illustrated downstream of a weir with fish pass on the River Severn, UK. The results show that each of the techniques can have a statistically significant effect on the estimated total water velocities and can strongly affect measures of vorticity. The obtained three-dimensional flow maps are suitable to describe the magnitude and orientation of the fish pass attraction flow in relation to competing flows and to highlight areas of increased vorticity.

scholarly journals Detiding ADCP Data in a Highly Variable Shelf Sea: The Celtic Sea

2005 ◽  
Vol 22 (1) ◽  
pp. 84-97 ◽  
Author(s):  
L. Carrillo ◽  
A. J. Souza ◽  
A. E. Hill ◽  
J. Brown ◽  
L. Fernand ◽  
...  
Keyword(s):  
Least Squares ◽  
Least Squares Method ◽  
Three Dimensional ◽  
Acoustic Doppler Current Profiler ◽  
Tidal Currents ◽  
Shelf Area ◽  
Residual Currents ◽  
Current Profiler ◽  
Adcp Data ◽  
Celtic Sea

Abstract This paper presents a comparison of two conventional detiding techniques carried out for ship-mounted acoustic Doppler current profiler (ADCP) data collected in the European shelf area of the Celtic Sea during the summer of 1998. One technique consisted of extracting the vertically averaged tidal currents obtained from a barotropic three-dimensional numerical tidal model. The second technique consisted of fitting the spatiotemporal ADCP data using least squares and polynomial spatial functions. In the least squares technique, the incorporation of zero velocity normal to the coast appears to improve the estimation of the tidal currents near the coast. Quantitative comparisons of the results from both techniques with historical current meter observations are shown. However, both methods showed limitations in accurately representing the tidal currents in the study area. Consequently, an alternative detiding technique is proposed. This technique consists of blending the tidal currents derived from the numerical model with those fitted to the ADCP data from the least squares method. Improved results were obtained using the blending technique. ADCP-derived residual currents were comparable with contemporaneous flows measured using drifting buoys and also with estimates obtained by geostrophic calculations.

scholarly journals Flow patterns over vegetation patches in the natural channel

2018 ◽  
Vol 40 ◽  
pp. 02059
Author(s):  
Yonguk Ryu ◽  
Joongu Kang ◽  
Un Ji ◽  
Sanghwa Jung ◽  
Changlae Jang ◽  
...  
Keyword(s):  
Cross Sections ◽  
Longitudinal Velocity ◽  
Three Dimensional ◽  
Acoustic Doppler Current Profiler ◽  
Low Flow ◽  
Cross Sectional ◽  
Hydraulic Conditions ◽  
Current Profiler ◽  
Vegetation Patches ◽  
Submerged Conditions

This study carried out experiments to investigate the effects of vegetation patches of rooted willows on the flow pattern. Stream-scale experiments on vegetated flows were performed for various hydraulic conditions: emergent and submerged conditions of vegetation. Vegetation patches were arranged by alternative bar formation and the flows in vegetated and non-vegetated sections were compared. Three-dimensional flow velocity was measured by ADV (Acoustic Doppler Velocimeter) and ADCP (Acoustic Doppler Current Profiler). Vertical, cross-sectional, and longitudinal velocity distributions were provided for different hydraulic conditions at various points. Flow velocities through the sparse patch were similar to those of non-vegetation area for low flow condition of emergent vegetation. Dense and submerged vegetation produced more complicated and non-uniform flows over the cross-sections of vegetation patches.

Characterization of a monolayer graphitic structure

1994 ◽  
Vol 52 ◽  
pp. 760-761
Author(s):  
X. Lin ◽  
X. K. Wang ◽  
V. P. Dravid ◽  
J. B. Ketterson ◽  
R. P. H. Chang
Keyword(s):  
Three Dimensional ◽  
Single Layer ◽  
Synthesis Process ◽  
Graphitic Structure ◽  
Positive Gaussian Curvature ◽  
Graphitic Sheet ◽  
Structural And Electronic Properties ◽  
New Material ◽  
Hexagonal Network

For small curvatures of a graphitic sheet, carbon atoms can maintain their preferred sp2 bonding while allowing the sheet to have various three-dimensional geometries, which may have exotic structural and electronic properties. In addition the fivefold rings will lead to a positive Gaussian curvature in the hexagonal network, and the sevenfold rings cause a negative one. By combining these sevenfold and fivefold rings with sixfold rings, it is possible to construct complicated carbon sp2 networks. Because it is much easier to introduce pentagons and heptagons into the single-layer hexagonal network than into the multilayer network, the complicated morphologies would be more common in the single-layer graphite structures. In this contribution, we report the observation and characterization of a new material of monolayer graphitic structure by electron diffraction, HREM, EELS.The synthesis process used in this study is reported early. We utilized a composite anode of graphite and copper for arc evaporation in helium.

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