Sinuous Channels Research Articles

Submarine canyons and slides in the central-west Otway Basin: their morphology, genesis, links to groundwater discharge and tsunamigenic potential

The morphology and development of several submarine canyons offshore southeast South Australia and western Victoria are described. The existence of three of those canyons had been foreshadowed in 1963 by N. Boutakoff, who thought them to be linked to ancient courses of the Glenelg River. These canyons occur on the outer continental shelf where their heads are situated in depths shallower than 1000 m. Sinuous channels are visible within two of the canyon heads, indicating that water and sediment may still travel downslope and cause erosion, and thus are geologically recent. Several other canyons are also documented and named. Two canyons are confined to depths below 3000 m; they may be much older and seem not to be linked to ancient river courses. They are also oblique to the upper canyons. The other characteristic feature of the area is the presence of numerous undersea slides. These occur at three specific depths (∼1200, ∼1500 and ∼1800 m) and are coincident with stratigraphic horizons in which continental groundwater flows have been identified in adjacent exploratory oil and gas wells drilled into the continental shelf. Sapping of groundwater may likely have occurred during very wet periods inland. We suggest that these undersea slides could be the first step in the formation of deep-sea canyons that are not necessarily linked to ancient river courses. We also postulate that the ‘sliding’ of large piles of sediment down the continental slope has tsunamigenic potential and may have occurred during significant wet climate on land. KEY POINTS Several deep-sea canyons and numerous submarine slides are documented along the continental shelf offshore the coastline of western Victoria and southeast South Australia in the Otway Basin. Some of these canyons are linked to previous courses of the Glenelg River, which changed over time in response to regional tectonic changes such as faulting and significant upwarping. The orientation of most of these canyons tends to align with ancient terrestrial lineaments that likely extend offshore. Sinuous channels within the upper canyon reaches are clearly visible and not infilled with sediment; they are likely active and linked to ongoing groundwater seepage. It is proposed that the underwater slides are generated by the submarine discharge of continental groundwater on the continental slope, at three specific water depths with discharge associated with particular lithologies. These slides may still be active. Superimposed slides may engender the formation of new canyons. The volume of some of these undersea slides is of tsunamigenic scale.

Planform Dynamics and Cut-Off Processes in the Lower Ucayali River, Peruvian Amazon

The Ucayali River is one of the most dynamic large rivers in the world, with high rates of channel migration regularly producing cutoffs. In the lower portion of the Ucayali River, before its confluence to the Marañon River where the Amazon River is born, the increase in water and sediment discharge triggers bends with secondary channels (transitional stage from purely meandering to anabranching), which influence the planform migration rates and patterns of the sinuous channels. Based on remote sensing analysis, a comparison of planform dynamics of bends with and without secondary channels is presented. For the case of a bend with secondary channels (Jenaro Herrera, JH), detailed field measurements for bed morphology, hydrodynamics, bed and suspended load are performed for low-, transitional- and high-flow conditions (August, February and May, respectively). Additionally, a two-dimensional depth average hydraulic model is utilized to correlate observed migrating patterns with the hydrodynamics. Results indicate that the secondary channels have disrupted typical planform migration rates of the main meandering channel. However, at high amplitudes, these secondary channels reduce their capacity to capture flow and start a narrowing process, which in turn increases migration rates of the main channels (meandering reactivation process), suggesting that an imminent cutoff along the JH bend is underway by pure lateral migration or by the collapse into the existing paleochannels.

Biogeomorphic recovery of a river reach affected by mining

AbstractEnvironmental changes are impacting river systems worldwide. These arise from factors such as flood magnitude–frequency changes, direct human management interventions, inadvertent human impacts on sediment supply and fluvial regimes and landscape‐scale changes in climate. Historical and active metal mining is significant in this regard. Here, we investigate morphodynamic changes within a reach of the River Ystwyth, Wales, since 1845. We analyse historical and contemporary information derived from maps, river flow records (1962–2021), metal analyses of sediment samples (1970s and 2021), ground geomorphological surveys (1970s and 1986–1987) and remotely sensed imagery (2001–2021) to investigate changes during a period of active metal mining followed by a century of post‐mining recovery. During the studied period, an initially meandering river was transformed into a braided one, subsequently reverting to a single sinuous channel. Sinuosity reduced from 1.31 in 1845 to 1.09 in 1982 before recovering to 1.39 in 2019. Inversely, the braiding index reduced from a maximum of 2.0 in 1987 to 1.5 in 2021. Evolution in planform was associated with a change from expansive bar formation and avulsion under braided conditions to lateral bar accretion and associated bank erosion along a sinuous single channel. The initial 19th‐century channel pattern and floodplain instability seems to have been related to mining sediment toxicity effects rather than a response to high sediment volumes, with recent recovery and channel style reversion being attributable to vegetation encroachment and biomass stabilization of the floodplain. Causal factors of recent recovery appear to be colonization by gorse (Ulex europeaus) in the absence of physical control measures and a reduction in grazing by the native rabbit population because of a disease‐induced decline in their numbers. These results highlight the importance of riparian vegetation in addition to sediment balance and hydrological processes in controlling fluvial responses to environmental changes.

Hydrodynamics and turbulence anisotropy for complex flow in a sinuous channel

Hydrodynamics and turbulence anisotropy for complex flow in a sinuous channel

Channel Migration Detection and Landuse/Landcover Changes for Barak River in Northeast India

Abstract In northeast India, Barak river is among one of the principal rivers, which is highly meandering in nature in its flood plain area.For infrastructural development and river protection works, it is essential to know the behavior of banklines shifting on landuse and landcover changes. This study is to evaluate the impact of bank lines shifting on land use and land cover changes. In order to fulfill the purpose of the present study 12 reaches with 41 cross-sections have been selected. The whole work has been done with the help of RS and GIS techniques using Landsat images and hybrid classification for the landuse and landcover classification. The result of the study shows that in the upper reach of the alluvial plain,there is an active shifting. Also, it is observed that at the lower reach, the river has moved in both north and south direction. It is observed that maximum migration rate is 130.2 m/year with a mean migration rate (9.43 m/year). The sinuosity estimated for the same reach with 12 bends is in the range 1.24 - 3.89. Among all the sections, the minimum and maximum changes of width are 0.26m and 249.93m respectively with an average value of 84.51m. It is found that the Barak river can be classified into sinuous channel (1.05 to 1.5), as well as meandering channel (>1.5).The investigation of changes in the pattern of land use land cover (LULC) of the Barak basin over 33 year’s period (1984-2017) shows that urban/built-up and agricultural land was increased gradually, e.g., urban increased by 40.6% for 1984-1992, 72.14% for 2002-2012, 180.15% for 1984-2017. While, agricultural land increased by 18.9% for 1984-1992, 41.15% for 1992-2002 and 93.20% for 1984-2017. In addition water bodies increased by 19% and 41.73% from 1984-1992 and 1984-2017 respectively. In contrast, dense vegetation decreased by 5.6% for 1984-1992 and 21.77% for 2002-2012 and 39.14% for 1984-2017. Open vegetation showed a decreasing tren by 11.1% for 1984-1992, 26.83% for 1992-2002, and 36.27% for 1984-2017. Rapid population growth, migration of rural people to urban, unawareness of biophysical limitations and poverty are some of the probable reasons behind the changes in the LULC. The results of the hybrid classification of the LULC of the Barak River for the Landsat 1(1984; MSS), Landsat 2 (1992; TM), Landsat 5 (2002; TM), Landsat 7(2012;ETM+) and Landsat 8(2017; OLI)showed overall classification accuracy of 90.83%, 86.67%, 90.56%,93.33%and 86.11% with overall kappa statistics of 0.8900, 0.8400, 0.8867, 0.9200 and 0.8333 respectively. The channel migration directly affects the land use and land use change and has direct effect on the flood plain dwellers of the study area. All the assessments of this study highlight a significant message of immense vulnerability of the Barak river and also provide news about geomorpho-logical instabilities of the study area

Frontogenesis, Mixing, and Stratification in Estuarine Channels with Curvature

Abstract Idealized numerical simulations were conducted to investigate the influence of channel curvature on estuarine stratification and mixing. Stratification is decreased and tidal energy dissipation is increased in sinuous estuaries compared to straight channel estuaries. We applied a vertical salinity variance budget to quantify the influence of straining and mixing on stratification. Secondary circulation due to the channel curvature is found to affect stratification in sinuous channels through both lateral straining and enhanced vertical mixing. Alternating negative and positive lateral straining occur in meanders upstream and downstream of the bend apex, respectively, corresponding to the normal and reversed secondary circulation with curvature. The vertical mixing is locally enhanced in curved channels with the maximum mixing located upstream of the bend apex. Bend-scale bottom salinity fronts are generated near the inner bank upstream of the bend apex as a result of interaction between the secondary flow and stratification. Shear mixing at bottom fronts, instead of overturning mixing by the secondary circulation, provides the dominant mechanism for destruction of stratification. Channel curvature can also lead to increased drag, and using a Simpson number with this increased drag coefficient can relate the decrease in stratification with curvature to the broader estuarine parameter space.

Numerical Study of Mixing Process by Point Source Pollution with Different Release Positions in a Sinuous Open Channel

The process of pollutant mixing is significantly influenced by secondary flow and turbulence in meandering rivers. To investigate the influence of different point source release positions on the pollutant mixing process in sinuous open channel flows, a 3D large-eddy simulation (LES) model based on OpenFOAM was established to simulate the process of passive scalar transport in a sinuous channel with a rectangular cross-section. After verification by a flume experiment, two sets of cases in which the point sources were arranged at identical intervals in spanwise and streamwise directions were configured to evaluate the mixing efficiency. The effect of flow structure, secondary motion, and the turbulent viscosity on the scalar transport and mixing was discussed. The distribution of scalar as well as the scalar flux was analyzed in detail, and the fluctuation characteristics were also described. The results demonstrate that due to the existence of secondary flow in the sinuous channel, different transverse and streamwise release positions of the point source have significant influence on mixing efficiency and spatial distribution of the pollutant. The point source placed near the center of the cross-section in transverse or near the apex of the bend in streamwise result in higher mixing efficiency. Mixing efficiency calculated by different indices can be different, which requires comprehensive assessment.

The paleoenvironment and depositional context of the Sumerian site of Abu Tbeirah (Nasiriyah, southern Mesopotamia, Iraq)

AbstractThe Sumerian culture flourished within the Tigris and Euphrates rivers floodplains and along their deltaic systems, which ca. 6000 yr were located ~250–260 km inland from the present Persian Gulf. Here, large floodplains and marshes were crossed by an intricate network of channels where several human settlements developed. In this paper, we describe in detail the paleoenvironmental context where the site of Abu Tbeirah (third millennium BC) developed, near the Sumerian capital of Ur. Our interdisciplinary approach, based on remote sensing and the geomorphological study of the area, as well as on sedimentological, paleontological, and paleobotanical analyses of trenches and boreholes deposits, reveals that the site developed along a sinuous channel in a floodplain and marshy environment, where several crevasse splays occurred. This channel was cut off following a flood event. The abandoned portion of the channel was exploited by residents and used as a small river harbor. Our research contributes to better define how the landscape of the site changed over the course of its history and how humans exploited water resources of the area during occupation of the site, a process that was pivotal for the development of the Sumerian culture.

Planform evolution of a sinuous channel triggered by curvature and autogenic width oscillations due to generic grain transport

We study the dynamics of an erodible sinuous channel subject to combined curvature and autogenic width oscillations. We find that generic grain transport (both bedload and suspended load transport) amplifies lateral stretching of the channel centerline and enhances the maximum width-variation amplitude and curvature ratio in their temporal dynamics by displaying a phase lag. However, in the initial and mature stages, the planform dynamics asymptotically approaches the conventional limits. The planform evolution is found to be influenced by four key parameters: Shields number, relative roughness, channel aspect ratio, and shear Reynolds number. The findings of this study, to the best of our knowledge, represent the first analytical investigation of the planform evolution of a sinuous channel driven by generic grain transport.

Sinuous channels east of Olympus Mons, Mars: Implications for volcanic, hydrological, and tectonic processes

The Late Amazonian volcanic plains east of Olympus Mons contain numerous channels and fossae. Channel formation hypotheses have included volcanic processes, flowing water, or a combination of both. To evaluate these hypotheses, we conducted detailed geomorphological and facies mapping at two sites containing channels and fossae representative of features in the region. Based on our mapping and morphological analyses using high resolution topography and images from HiRISE and CTX data, we classified channels into three types, and fossae into two types. Channel Type 1 and Type 2 are consistent with the morphology of lava channels, however, we found no evidence of channel formation due to thermo-mechanical erosion. Additionally, we calculated the potential for lava to achieve turbulent flow within our two study sites and found it unlikely. Channel Type 3 is consistent with fluvial bedrock erosion, likely sourced from erupted groundwater that entrained regolith into lahar-like flows. Fossae are classified as linear (Type L) or arcuate and branched (Type A). Type L fossae are interpreted to be surface fractures associated with dike emplacement, whereas Type A fossae are interpreted to be surface fractures due to sill emplacement, which may have melted buried ice deposits and generated meltwater floods. Type 1 and Type 2 channels are associated with Type L fossae and fissure-fed effusive eruptions of lava. In contrast, Type 3 channels are co-located with Type A fossae, and are likely due to outbursts of groundwater possibly related to sill emplacement. We attribute the formation and distribution of channels and fossae throughout the plains east of Olympus Mons to be a consequence of the region’s evolving states of stress, which are predominantly influenced by the loading of Olympus Mons.

Deepwater seismic facies and architectural element interpretation aided with unsupervised machine learning techniques: Taranaki basin, New Zealand

The use of unsupervised machine learning (ML) methods such as self-organizing maps (SOMs), has gained a significant foothold within the seismic interpretation community to enhance results and help identify similar patterns in the data. Workflows for each geological setting become, however, necessary. We analyzed a series of geometrical, instantaneous, spectral, and textural seismic attributes to provide multi-attribute input combinations that, with SOMs, allow for a proper interpretation of architectural elements in deepwater settings. By studying the Miocene section within the Pipeline 3D seismic dataset in southern Taranaki Basin, we show that GLCM entropy, RMS amplitude, sobel filter similarity, and frequencies seismic attributes used as inputs into the SOM enhance the interpretation of the features of interest, initially overlooked by single attributes analysis. This method had not been applied in the area yet. Results allow understanding and delineating architectural elements of deepwater systems, such as mud- and sand-filled channels, mass transport deposits (MTDs), and marine shales in the basin floor. Additionally, more minor features such as levees, overbank deposits, and sand waves are better mapped. The use of the Pukeko well helped to understand the system's evolution, which we interpret as a fan system incised by younger, more sinuous channels. Overall, the system turns more mud-prone as it becomes younger (upwards). Our study contributes to understanding the paleogeomorphology of the area, which can help optimize drilling plans, whereas our method offers three input attribute combinations for SOMs that can be applied in similar geological settings to aid in the interpretation optimization process.

Sediment gravity-flow deposits in Late Cretaceous Songliao postrift downwarped lacustrine basin, northeastern China

The Songliao Basin is a large Cretaceous nonmarine petroliferous postrift downwarped basin in northeastern China. Deep lake channel-levee-lobe and slope fan deposits are identified within six depositional sequences that span from the Turonian to early Coniacian upper part of the fourth member of the Quantou Formation and Qingshankou Formation to the early Campanian second member of the Nenjiang Formation. Research on the sediment gravity-flow systems in the Songliao Basin has broad application for understanding the sedimentary processes and pattern of sediment gravity-flow systems, and predicting the presence of good sandstone reservoirs within postrift downwarped lacustrine basins. Research results show that the channel-levee-lobe deposits are present within sequences in the first member of the Qinshankou Formation and the first member of the Nenjiang Formation. The straight channel levees and slope fans were on high-gradient slopes, whereas the sinuous channel levees were on low-gradient slopes. The straight-to-sinuous channel levees, fed by northeastern deltaic subaqueous distributary channels, extend for 15–70 km, predominantly within transgressive-to early highstand system tracts, which terminated in bifurcated or small lobes. The channel-levee-lobe and slope fan deposits sourced from western deltas were deposited basinward of the syndepositional flexural slope-break zones controlled by deep-seated faults. The falling trajectories of the paleoshorelines during the highstand and lowstand systems tracts and large sediment fluxes during the transgressive systems tracts resulted in the development of the slope fans and channel-levee-lobes. Lakebed paleorelief influenced the channel forms. Sand bodies within the channel-levee-lobes and slope fans, encased within organic-rich source rocks, represent new significant targets for hydrocarbon exploration.

Generation of Overspill Pyroclastic Density Currents in Sinuous Channels

AbstractDue to their mobility, high velocities, and common occurrence, small‐volume pyroclastic density currents (PDCs) represent a major hazard around volcanoes. Small‐volume events are particularly sensitive to topography and channelization into drainage basins. Understanding the flow transition initiated by avulsion or overspill from valley confined PDC to unconfined PDC is necessary to mitigate their damage. We present three‐dimensional multiphase models of channelized PDCs and link the generation of overspill currents to channel geometry (width, depth, and curvature). Our simulation geometries span the range of natural channels commonly found in stratovolcanic landforms. Channels help inhibit ambient air entrainment into the underflow and can maintain and deliver material with minimal cooling during transport. We show that the main avulsion mechanism can include significant portions of the insulated underflow layer from the channel leading to a dangerously hot overspilled current. In all sinuous channel simulations, the underflow of the current becomes superelevated when it encounters bends and is able to overwhelm channel walls. The amount of mass overspilled is a function of channel curvature. Superelevation of the current increases with channel curvature and decreasing channel width but is underestimated using traditional estimates of superelevation due to the lack of the free surface in these flows. We also identify the occurrence of buoyant plume and secondary overspill events due to cross stream flow within the channel which would produce complex deposits associated with overspill events.

Channel and inter-channel morphology resulting from the long-term interplay of alongslope and downslope processes, NE Rockall Trough, NE Atlantic

With this contribution we use a pair of overlapping 3D seismic surveys and two exploration wells to document the response of long-lived slope channels to the onset of bottom currents sweeping the lower slope in the NE Rockall Basin, offshore Ireland. Downslope gravity current activity, linked to a phase of uplift, prevailed throughout the Eocene and led to the formation of multiple channels, most notably a large-scale sinuous channel complex (Channel 4 Complex) tied to a persistent sediment entry point on the margin. Channels fed lobes on the floor of the basin, with increased axial tilting forcing gravity currents to flow parallel to the base of slope. A phase of margin-wide differential subsidence and basin deepening in the Late Eocene then activated bottom current circulation across the basin. Northward-flowing bottom currents first erosionally refashioned the lower slope creating a prominent unconformity with contourites that then initially forming infill drifts. Bottom currents swept along and obliquely upslope, building plastered drifts that straddled the lower sections of the still active channels. The drifts modified and amplified the spurs separating the active channels, with interaction between along and downslope processes accreting sediment that built and maintained channel relief and allowed the channel mouths to extend further basinward over and across the earlier lobes. Contourite-forced channel extension on account of lower slope depositional re-profiling represents another manifestation of the interplay between slope channels and bottom currents. In the case of NE Rockall, the accreted base of slope wedge and mounded geometry resembles similar features elsewhere along the eastern Rockall margin. Those have previously been ascribed to mass-transport and base-up channel initiation, however, the similarities are so striking that we propose that these also are the result of lower slope re-profiling by bottom currents.

Evolution of Deep-Water Sinuous Channel Offshore Cameroon, West Africa, Using 3D Seismic Data

Using newly acquired 3D seismic data, the deep-water sinuous channel has been discovered in the Miocene sequence on the continental margin of Cameroon, West Africa. The investigation is using high-resolution 3D seismic data, covering an area of 1500 km2, with the water depth ranging from 400 m - 2000 m. Two submarine channel systems have been documented in the northern part of the study area, the offset stacked channel and North-Northeast – Southwest channel. The offset stacked channel dimension is about 3 km wide, c. 20 km long and c. 500 ms TWT thick, extending from east to west. The evolution of this channel can be divided into three stages based on the changes in channel scale, geometry, and fill type. In the initial stage, the channel is characterized as symmetry ‘U’ shaped, bidirectional onlap, high amplitude reflections, inferring to high energy flow and sand-prone channel fill. In the following stages, the channel reduced the size and flow energy. North-Northeast – Southwest channel developed at the end of the Miocene. It is c. 3 km wide, 20 km long, 50 ms TWT thick, indicating a new sediment source for the study area. At the end of the Miocene, both channel systems show a high sinuously as an indicator of low energy flows. Uplift in the Late Miocene possibly leads to the compacted channel complex which is appeared in the anticline form, giving a great hydrocarbon trap potential for the study area.

Re-interpretation of ‘hummocky moraine’ in the Gaick, Scotland, as erosional remnants: Implications for palaeoglacier dynamics

Many glaciated valleys in Scotland contain distinctive, closely spaced ridges and mounds, which have been termed ‘hummocky moraine’. The ridges and mounds are widely interpreted as ice-marginal moraines, constructed during active retreat of mainly temperate glaciers. However, hummocky terrain can form by various processes in glacial environments, and it may relate to a range of contrasting glaciodynamic regimes. Thus, detailed geomorphological and sedimentological studies of hummocky surfaces in Scottish glaciated valleys are important for robust interpretations of former depositional environments and glacier dynamics. In this contribution, we examine irregularly shaped ridges and mounds that occur outside the limits of former Loch Lomond Readvance (≈Younger Dryas; ~12.9–11.7 ka) glaciers in the Gaick, Central Scotland. These ridges and mounds are intimately associated with series of sinuous channels, and their planform shape mimics the form of the adjacent channels. Available exposures through ridges in one valley reveal that those particular ridges contain lacustrine, subglacial, and glaciofluvial sediments. The internal sedimentary architecture is not related to the surface morphology; thus, we interpret the irregularly shaped ridges and mounds as erosional remnants (or interfluves). Based on the forms and spatial arrangement of the associated channels, we suggest that the ridges and mounds were generated by a combination of ice-marginal and proglacial glaciofluvial incision of glaciogenic sediments. The evidence for glaciofluvial incision, rather than ice-marginal moraine formation, at pre-Loch Lomond Readvance glacier margins in the Gaick may reflect differences in glaciodynamic regimes and/or efficient debris delivery from the glacier margins to the glaciofluvial systems.

Laterally accreting sinuous channels and their deposits: The Goldilocks of deep-water slope systems

ABSTRACTChannels with a sinuous planform are common in both continental and deep-marine environments on Earth, and similarly in high-resolution images of the surface of Mars. Whereas common in rivers, continuous lateral channel migration and point-bar deposition appear to be much less common in the deep sea. In the bends of rivers, near-bed flow driving point bar growth results from a cross-flow superelevation of the water surface that sets up a lateral hydrostatic pressure gradient driving an inward-directed flow near the bed. However, in deep-marine systems the surface between the turbidity current and overlying ambient fluid sits well above the channel margins, and therefore precludes a similar lateral superelevation of the current top. Here it is argued that the cross-flow component is related to a density gradient that mimics the effect of the hydrostatic pressure gradient in rivers, and develops as coarse suspended particles that experience little uplift, and therefore negligible overspill, become concentrated along the outer bank. This condition develops best in a two-part suspension made up of a highly concentrated, unstratified basal plug of coarse sediment overlain sharply by a dilute cloud of much finer sediment—a density structure that differs from the more typical upward exponential decrease in density. The abundance of coarse and fine sand, but depletion in the intermediate grain size fraction, is related to transgressive shelf processes and its influence on sediment supplied to the system, and in turn, the flow structure of the current. It is under these seemingly uncommon granulometric conditions that continuous laterally migrating channels, and accordingly, riverine-like point-bar deposition, is most common in the deep sea.

Gene-expression programming for calculating discharge in meandering compound channels

Computation of flow in natural channels is the key to the solution of numerous engineering problems particularly at the time of flood. Therefore, different approaches have been incorporated for accurate estimation of flow discharge in compound meandering channels. The present work focuses on developing an empirical model for estimating the flow of meandering compound channels using gene-expression programming (GEP) by considering four non-dimensional parameters viz Relative Depth, Sinuosity, Coherence Parameter, and Discharge Ratio (Qvdm/Qbf). The model developed for the meandering compound channels is best suited for sinuosity in the range of 1.04–2. To measure adequacy of the model, the results of the developed model are compared with various discharge estimation methods such as the Single Channel Method (SCM), Divided Channel Method (DCM), Meander Belt Method (MBM), Modified Divided Channel Method (MDCM), Interacting Divided Channel Method (IDCM), and Coherence Method (COHM). Results indicate that the proposed GEP model predicted the ratio of total discharge in compound channel (Qt) to the bank-full discharge (Qbf) in main channel satisfactorily with root mean square error of 0.15 and 0.19 for training and testing dataset, respectively. The developed model is also used to validate with higher sinuous channels having sinuosity exceeding 2.0. Finally, the model was successfully validated with natural flood conditions of River Baitarani, India (sinuosity of 1.334) giving the minimum errors in terms of mean absolute square error of 0.885 and 0.882 for the two overbank flow depths of 7.5 and 8.63 m, respectively.

Turbulence Anisotropy in a Sinuous Channel with Downward Seepage

Turbulence Anisotropy in a Sinuous Channel with Downward Seepage

Ordered structure of interlayer constructed with metal-organic frameworks improves the performance of lithium-sulfur batteries

Lithium-sulfur (Li-S) battery has attracted intensive attention in the realm of energy storage owing to its high theoretical capacity and energy density. However, the shuttle effect of soluble lithium polysulfides (LiPSs) between electrodes results in rapid capacity degradation. Herein, a strategy which combines the design of both chemical interaction and microstructure of interlayer was proposed to suppress the shuttle effect. The chemical interaction between different functionalized MOFs and LiPSs was systematically studied to find the best candidate. Furthermore, an interlayer with ordered structure was constructed via the layer-by-layer assembly of metal-organic frameworks (MOFs) on graphene (UiO-66-NH2@graphene) to create sinuous channels which can better impede the diffusion process of LiPSs by the strong adsorption of MOF toward LiPSs. Consequently, in comparison to the battery with a bare separator, the ordered interlayer increased the initial discharge capacity of battery by 28.98% at 1.0 C and lowered the capacity decay rate remarkably from 0.10% to 0.067% per cycle, indicating that the design of chemical interaction and microstructure paves the way for high-performance Li-S batteries.