scholarly journals Bank Erosion of A Main Channel and Scouring of A Side Channel in A River in An Alluvial Fan Reach

1993 ◽  
Vol 37 ◽  
pp. 623-630
Author(s):  
Hajime MIWA
Keyword(s):  
Bank Erosion ◽  
Main Channel ◽  
Alluvial Fan ◽  
Side Channel

scholarly journals Hydraulic Evaluation of the Levee System Evolution on the Kurobe Alluvial Fan in the 18th and 19th Centuries

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4406
Author(s):  
Tadaharu Ishikawa ◽  
Hiroshi Senoo
Keyword(s):  
Channel Capacity ◽  
Flood Control ◽  
River Flow ◽  
Global Climate ◽  
Flow Simulation ◽  
Japan Sea ◽  
Main Channel ◽  
Alluvial Fan ◽  
Flood Peak ◽  
Levee System

The development process and flood control effects of the open-levee system, which was constructed from the mid-18th to the mid-19th centuries, on the Kurobe Alluvial Fan—a large alluvial fan located on the Japan Sea Coast of Japan’s main island—was evaluated using numerical flow simulation. The topography for the numerical simulation was determined from an old pictorial map in the 18th century and various maps after the 19th century, and the return period of the flood hydrograph was determined to be 10 years judging from the level of civil engineering of those days. The numerical results suggested the followings: The levees at the first stage were made to block the dominant divergent streams to gather the river flows together efficiently; by the completed open-levee system, excess river flow over the main channel capacity was discharged through upstream levee openings to old stream courses which were used as temporary floodways, and after the flood peak, a part of the flooded water returned to the main channel through the downstream levee openings. It is considered that the ideas of civil engineers of those days to control the floods exceeding river channel capacity, embodied in their levee arrangement, will give us hints on how to control the extraordinary floods that we should face in the near future when the scale of storms will increase due to the global climate change.

scholarly journals Interactions between channels and tributary alluvial fans: channel adjustments and sediment-signal propagation

2019 ◽  
Author(s):  
Sara Savi ◽  
Stefanie Tofelde ◽  
Andrew D. Wickert ◽  
Aaron Bufe ◽  
Taylor F. Schildgen ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Signal Propagation ◽  
Main Channel ◽  
Alluvial Fan ◽  
Sediment Supply ◽  
Alluvial Fans ◽  
Fluvial System ◽  
Channel Network ◽  
Fluvial Deposits ◽  
The Impact

Abstract. Climate and tectonics impact water and sediment fluxes to fluvial systems. These boundary conditions set river form and can be recorded by fluvial deposits. Reconstructions of boundary conditions from these deposits, however, is complicated by complex channel-network interactions and associated sediment storage and release through the fluvial system. To address this challenge, we used a physical experiment to study the interplay between a main channel and a tributary under different forcing conditions. In particular, we investigated the impact of a single tributary junction, where sediment supply from the tributary can produce an alluvial fan, on channel geometries and associated sediment-transfer dynamics. We found that the presence of an alluvial fan may promote or prevent sediment to be moved within the fluvial system, creating different coupling conditions. A prograding alluvial fan, for example, has the potential to disrupt the sedimentary signal propagating downstream through the confluence zone. By analyzing different environmental scenarios, our results indicate the contribution of the two sub-systems to fluvial deposits, both upstream and downstream of the tributary junction, which may be diagnostic of a perturbation affecting the tributary or the main channel only. We summarize all findings in a new conceptual framework that illustrates the possible interactions between tributary alluvial fans and a main channel under different environmental conditions. This framework provides a better understanding of the composition and architecture of fluvial sedimentary deposits found at confluence zones, which is essential for a correct reconstruction of the climatic or tectonic history of a basin.

Marangoni Asymmetrical Instability in a T-Junction Microchannel With an Open Outlet

2012 ◽  
Author(s):  
Zhenhai Pan ◽  
Hao Wang
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Marangoni Number ◽  
Marangoni Convection ◽  
Main Channel ◽  
The Other ◽  
Side Channel ◽  
Single Vortex ◽  
Steady Convection ◽  
Critical Intensity

The Marangoni convections in microchannels are of interest in various applications such as heat transfer, material and microfluidics. In this paper, the Marangoni asymmetrical instability at a T-junction in a microchannel is investigated. The T-junction is formed by a main channel which water going through and a side channel which is open to the ambient. A convex meniscus is formed in side channel near the T-junction, evaporating/volatizing into the ambient. The consumption of water due to the evaporation is compensated by the supply from the main channel. It is found that for weak evaporations, the evaporation-induced Marangoni convections are symmetrical. However, when the evaporation reaches a critical intensity, the symmetrical Marangoni convection becomes unstable and evolves into an asymmetrical one, with one single vortex under the meniscus. More interestingly, the vortex creates a steady convection through the main channel from its one end to the other, just like a pump. The pumping flow rate is found linearly correlated with the Marangoni number at the T-junction.

scholarly journals FRET-Based Detection of Enzymatic Reaction of Botulinum on Microfluidic Device

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Young Min Bae ◽  
Seung Oh Jin ◽  
Insoo Kim ◽  
Ki Young Shin
Keyword(s):  
Microfluidic Device ◽  
Botulinum Toxin A ◽  
Enzymatic Reaction ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Reaction Chamber ◽  
Main Channel ◽  
Side Channel ◽  
Peptide Substrate ◽  
Electric Voltage

A microfluidic device was implemented to detect the enzymatic reaction of botulinum toxin A (BTA) using Förster resonance energy transfer (FRET). The microfluidic device comprised a main channel having two loading zones, a reaction chamber and a side channel perpendicular to the main channel. The reaction chamber defined by weir in the main channel was packed with microbeads. The movement of the peptide substrate and the BTA in the microfluidic device was controlled by electrophoresis, and the enzymatic reaction of the BTA was detected through the changes of the fluorescence intensity in the reaction chamber. As a result, it was observed that the enzymatic reaction was affected by the electric voltage applied for the movement of the BTA and the peptide and improved by packing the microbeads in the reaction chamber. The microfluidic device provides the tool to investigate the proteolysis of the substrate by the BTA.

scholarly journals Study of a debris torrent in the Dolomites, Italy

2000 ◽  
Vol 22 ◽  
Author(s):  
Elena Biscuola ◽  
Maria Chiara Turrini
Keyword(s):  
Grain Size ◽  
Debris Flows ◽  
Main Channel ◽  
Alluvial Fan ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Historical Reconstruction ◽  
Landslide Area ◽  
Precipitation Records ◽  
The Town

The Dolomites are situated in a region characterised by the presence of widespread debris flows, which originate at the foot of sub-vertical rocky walls and involve the underlying debris talus. These flows are characterised by the scantiness of the planimetric surface in the watershed and, when they are not channelled, by the variability of the courses from one event to another. This paper describes the study of a channelled debris flow or debris torrent, which periodically jeopardises the built-up area of San Vigilio di Marebbe (Bolzano). This town is located on a large alluvial fan formed by the torrents Ermo and Fojed6ra. The beds of both torrents are constantly full of debris, which is partly contained by many dams and mostly carried away by the water that undercuts the banks. The Fojedora, in particular, which until 1971 ran through the town carrying with it considerable amounts of debris, regularly damaged the town. As a result of these incidents, the last part of the course of the Fojed6ra was artificially diverted into the Ermo by the construction of a 4 m high and 320 m long dyke. In this way the flows, which continued to run through the torrent in the following years, were confined in the channel, and the only danger was that posed by the damming of the main channel into which the torrent Fojed6ra-Ermo flows. The last important event took place on 27 July 1995 following a short but bad cloud burst in the upper reaches. It mobilised a considerable amount of debris and gave rise to a flow, which was contained by the dyke, and temporarily obstructed the main torrent and the valley floor. The aim of the study was to reveal the mechanisms that might trigger off the flows, to analyse the morphometry of the deposits in order to characterise these deposits in terms of grain size, and to assess the possibility of damage to the infrastructure. The work was carried out in the following phases: - a historical reconstruction of past events from both historical documents and the "memories" of the oldest inhabitant s of the town: - a study of the precipitation records of two meteorological stations located near the landslide area; and - a topographical reconstruction of the flow route in order to map the main morphological elements , such as channels, scarps, banks, and lobes, and to carry out the grain size analysis of sediments. Detailed mapping of the alluvial fan by mean s of overlaying slope and land use maps was aimed at evaluating whether a possible flow that was not contained by the dyke might reach San Vigilio di Marebbe.

scholarly journals Interactions between main channels and tributary alluvial fans: channel adjustments and sediment-signal propagation

2020 ◽  
Vol 8 (2) ◽  
pp. 303-322
Author(s):  
Sara Savi ◽  
Stefanie Tofelde ◽  
Andrew D. Wickert ◽  
Aaron Bufe ◽  
Taylor F. Schildgen ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Signal Propagation ◽  
Main Channel ◽  
Alluvial Fan ◽  
Sediment Supply ◽  
Alluvial Fans ◽  
Fluvial System ◽  
Channel Network ◽  
Fluvial Deposits ◽  
The Impact

Abstract. Climate and tectonics impact water and sediment fluxes to fluvial systems. These boundary conditions set river form and can be recorded by fluvial deposits. Reconstructions of boundary conditions from these deposits, however, is complicated by complex channel–network interactions and associated sediment storage and release through the fluvial system. To address this challenge, we used a physical experiment to study the interplay between a main channel and a tributary under different forcing conditions. In particular, we investigated the impact of a single tributary junction, where sediment supply from the tributary can produce an alluvial fan, on channel geometries and associated sediment-transfer dynamics. We found that the presence of an alluvial fan may either promote or prevent the movement of sediment within the fluvial system, creating different coupling conditions. By analyzing different environmental scenarios, our results reveal the contribution of both the main channel and the tributary to fluvial deposits upstream and downstream from the tributary junction. We summarize all findings in a new conceptual framework that illustrates the possible interactions between tributary alluvial fans and a main channel under different environmental conditions. This framework provides a better understanding of the composition and architecture of fluvial sedimentary deposits found at confluence zones, which can facilitate the reconstruction of the climatic or tectonic history of a basin.

Dielectrophoresis Separation of Colon Cancer Cell

2009 ◽  
Author(s):  
Fang Yang ◽  
Xiaoming Yang ◽  
H. Jiang ◽  
P. Wood ◽  
W. Hrushesky ◽  
...  
Keyword(s):  
Cancer Cell ◽  
Cancer Diagnosis ◽  
Collection Efficiency ◽  
Hct116 Cell ◽  
Main Channel ◽  
Colon Cancer Cell ◽  
Design Flow ◽  
Side Channel ◽  
Chip Design ◽  
Electric Activation

Separation of cancer cells from the other biological cells is important for clinical cancer diagnosis and cancer treatment. In this presentation, we use conventional dielectrophoresis (c-DEP) in a microfluidic chip to manipulate and collect colorectal cancer HCT116 cell. It is noticed that at particular AC frequency band, the HCT116 cell are deflected to a side channel from a main channel clearly after the electric activation. This motion caused by negative DEP can be used to separate the cancer cell from others. In this manuscript, we report the chip design, flow condition, the DEP spectrum of the cancer cell, and the separation and collection efficiency as well.

Orientation of groins for wide and dynamic lowland rivers

2014 ◽  
Vol 11 (4) ◽  
pp. 431-440
Author(s):  
M. Alauddin ◽  
T. Tsujimoto
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Bank Erosion ◽  
Main Channel ◽  
High Flow ◽  
Local Scour ◽  
Low Flow ◽  
Alluvial Rivers ◽  
Lowland Rivers ◽  
2D Numerical Model

Alluvial rivers at lowland are very complex in nature. Severe bank erosion at high flow and undue sedimentation at low flow are very common there. Groins are not functioning successfully with their present arrangements. This study investigates various orientations of groins to identify the optimum one for the effective functioning at high flow and low flow both. A 2D numerical model, RIC-Nays is utilized upon confirmation through detailed experimental data. Two types of groins: non-permeable and permeable, and four orientations: 100°, 90°, 80° and 70° to the bank line downstream are considered. Computation reveals that smaller angled groins function better through deepening the main channel and minimizing the local scour, except deposition near bank reduces.

September: Alternate Realities

2019 ◽  
Author(s):  
Ellen Wohl
Keyword(s):  
Brown Algae ◽  
Forest Floor ◽  
Water Surface ◽  
Main Channel ◽  
Side Channel ◽  
Small Patch ◽  
The Third ◽  
Side Channels ◽  
Beaver Dam ◽  
Strong Winds

The first week of September mostly feels like summer. The air on the dry terrace bordering the beaver meadow is richly scented with pine. Purple aster, blue harebells, and tall, yellow black-eyed Susan still bloom. Fungi are more abundant on the forest floor, and the tiny, purplish berries of kinnikinnick are sweet to the taste. The air is warm in the sunshine, but strong winds hurry rain showers through at intervals. Patches of last year’s snow linger on the surrounding peaks, even as the first light snows have already fallen in the high country. Down in the beaver meadow, the leaves of aspen, willow, birch, and alder are starting to assume their autumn colors. Here and there a small patch of yellow or orange appears among the green. Blades of grass have a pale orange tint and the strawberry leaves have gone scarlet, even as white asters, purple thistles, and a few other flowers continue to bloom. The creek is noticeably lower, its cobble bed slick with rust-brown algae. Exposed cobble and sandbars have grown wider as the water has shrunk back from the edge of the willows, and the main channel is easy to cross on foot. The clear water is chillingly cold in both the main channel and the side channels. The smaller side channels no longer flow, and a drape of mud mixed with bits of plants covers the cobbles. Wood deposited a year ago has weathered to pale gray. The older, marginal beaver ponds have shrunk noticeably, and the water is lower in the main ponds, where tall sedges now lie bent on the top of the declining water surface. The beavers remain active: following fresh moose tracks, I come on a newly built beaver dam on a small side channel. By the third week of September, autumn has clearly arrived in the mountains. The air remains quite warm during the day, but nights of frost are swiftly bringing out the autumn colors. Whole stands of willows and aspen now glow golden or pumpkin-orange.

scholarly journals The Effect of Variations of Flow from Tributary Channel on the Flow Behavior in a T-Shape Confluence

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 614
Author(s):  
Aliasghar Azma ◽  
Yongxiang Zhang
Keyword(s):  
Fluid Transport ◽  
Flow Behavior ◽  
Surface Profile ◽  
Main Channel ◽  
Turbulence Energy ◽  
Side Channel ◽  
Head Losses ◽  
Flow Parameters ◽  
Separation Plate ◽  
Transport Channels

Channel confluences are of the common structures in fluid transport channels. In this study, a series of numerical simulations were performed, utilizing a 3D code to investigate the reaction of the flow parameters and vortical structure to the variations in flow discharge and its Froude number from both main channel and tributary branch in a T-shape junction. The code was calibrated with the experimental data. Parameters, including the velocity, the turbulence energy, stream surface profile, head losses, and the transverse flow motions, were considered in different situations. It was concluded that increasing the ratio of discharge of flow from side-channel to the main channel (Q*) increased the area and power of the recirculation zone, as well as the width of separation plate downstream of the confluence, while it reduced the area of the stagnation zone (or the wake vortex) within the side-channel. It was also indicated that increasing the discharge ratio from side-channel resulted in an increase in the upstream water level in the main channels, which was dependent on the upstream discharge.

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