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In this work, surface/interface effects for pull-in voltage and viscous fluid velocity effects on the dimensionless natural frequency of fluid-conveying multiwalled piezoelectric nanosensors (FC-MWPENSs) based on cylindrical nanoshells is investigated using the Gurtin–Murdoch surface/interface theory. The nanosensor is embedded in a viscoelastic foundation and subjected to nonlinear van der Waals and electrostatic forces. Hamilton’s principle is used to derive the governing and boundary conditions and is also the assumed mode method used for changing the partial differential equations into ordinary differential equations. The influences of the surface/interface effect, such as Lame’s constants, residual stress, piezoelectric constants and mass density, are considered for analysis of the dimensionless natural frequency with respect to the viscous fluid velocity and pull-in voltage of the FC-MWPENSs.

ABSTRACT: Hydropower with a small elevation change from inlet to outlet, known as “low-head” hydropower, is a relatively untapped resource for reliable green power generation. One major barrier to entry is the cost of the components needed to generate the power. Each installation site is unique, with various head levels, flow rates, and other unique site characteristics that drive up the cost of development and installation. As a result, custom-made components are necessary because the sites are intrinsically inefficient. However, customized parts are generally more expensive to manufacture than ready-made parts. Often times, the cost of custom-made components is so high that the low-head hydropower installation becomes non-viable. Additive manufacturing offers the ability to make custom components, ideal for one-off applications, at low costs that are well suited for the needs of low-head hydropower. Indirect additive manufacturing, such as making tools or dies rather than end use components, can also be used to make low-cost composite tooling as needed for these custom applications. This paper explores the use of additive manufacturing, both directly and indirectly, to produce the components of a turbine system for a low-head hydropower site. The parts were designed to form a unique modular system, which saves time for future designs and iterations. The system has operated for more than three years without failure at a test site in Wisconsin, USA. This work serves as a basis for future application of AM to low-head systems, in which the modular components can be customized for each unique hydropower installation.

The presence of macroroughness elements directly affects the flow velocity in mountain headwater streams. Hydraulic roughness is the dominant resistance to flow caused by objects protruding into the water, but it is not measurable in the field. This study quantified the reach-average hydraulic roughness based on the channel morphology in two mountain streams. The average flow velocities of the reaches were measured using the dye-tracing method. The magnitude of the hydraulic roughness was derived from the grain size of the streambed materials (D50 and D84) and the cross-sectional/longitudinal bed roughness. The observations for low flows (0.04–0.43 m2/s discharge per unit width) indicated that the longitudinal 90% inter-percentile range ( I P R 90 L ) seemed to have considerable merit in examining the influences of large roughness elements on flow conveyance. A dimensionless hydraulic geometry relation that can reflect the field measurements over a limited range of hydraulic characteristics was also developed for estimating the reach-average flow velocity in steep and rough streams. Thus, the research framework used appears to provide a reliable method of quantifying reach-average hydraulic roughness from local data in mountain headwater streams. [ABSTRACT FROM AUTHOR]

The process of icing involves the freezing of overflow layers, on ground or within streams, and results in ice bodies called "aufeis" that are common in most northern landscapes. Knowledge about aufeis is still limited despite the cold region engineering challenge they represent. Understanding the causes of overflow events leading to aufeis development represents a key for the prediction, mitigation, and management of this geohazard and can also support the planning and design of infrastructure in the North. This paper introduces a practical classification for the diverse range of overflow processes that generate aufeis, including under-represented processes, such as the instability of winter streamflow. Importantly, it distinguishes flow conveyance from water supply overflow processes and describes the temporal aspect of icing intensity. Finally, research topics are proposed to improve our understanding of aufeis, including their predictability, the impact of climate change on their occurrence and extent, and stream morphology–aufeis interaction. [ABSTRACT FROM AUTHOR]

A paramount determinant in the selection of irrigation canal overflow configurations resides in their flow conveyance capacity. This overflow capacity is contingent upon the effective length and geometric characteristics of the weir. In the present investigation, the hydraulic performance and discharge coefficient (Cd) of circular-crested weir were scrutinized through the utilization of FLUENT software. Specifically, the study delved into the impact of geometric parameters, namely the radius and height of the crest, on these hydraulic aspects. Following the execution of calibration and validation procedures using FLUENT in conjunction with laboratory-derived data, the outcomes of the simulation revealed that augmenting the radius of the crest led to a corresponding escalation of 144.28% in the maximum pressure exerted on the crest and a 6.84% increase in flow depth. Conversely, the maximum velocity and Cd experienced reductions of 6.84% and 7.82%, respectively. The elevation of the weir height exhibited negligible influence on the maximum pressure magnitude at the crest. Contrastingly, a reduction in weir height constricted the range of pressure variations on the crest, indicating a more limited domain of pressure changes. Elevating the weir height induces a notable augmentation in the maximum flow velocity at the crest by 44.36%, concomitant with a reduction in both the depth and Cd by 52.66% and 68.96%, respectively. [ABSTRACT FROM AUTHOR]

In drainage and sewerage systems, vertical dropshafts are commonly used to convey water flow from high to low elevations. When the underground tunnel is surcharged, the lower part of the shaft is submerged. The impact of falling water on the free surface in the dropshaft entrains a vast amount of air, leading to the transport or entrapment of air in the tunnel, causing undesirable effects such as the reduction in flow conveyance capacity or air blowback. In this study, a comprehensive series of experiments was performed to study the influence of flow variables on the flow regimes in a submerged dropshaft connected to a horizontal tunnel. The air-water flow in the dropshaft was recorded using high-speed imaging, with air concentration and high-frequency pressure measurements. The experiments showed that the flow in the dropshaft-tunnel system can be classified into four regimes: (I) bubbly column flow, (II) rising slugs, (III) instability and surging, and (IV) net air transport in the tunnel, based on the dropshaft Froude number and the ratio of dropshaft diameter to tunnel diameter. [ABSTRACT FROM AUTHOR]

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Flow control programs on regulated rivers can improve winter flow conveyance for hydropower operations. On the Upper Nelson River, station flows at Jenpeg Generating Station are reduced during freeze-up to promote formation of a smooth ice cover in often turbulent upstream areas. This ice cover reduces the risk of frazil generation, which could otherwise result in blockages and subsequent energy losses. In this study, a characterization of freeze-up conditions for the Upper Nelson River is presented through 15 years of historical observations, supplemented by a short-term detailed monitoring program (2015–2018). Observations of rapid leading edge celerity are associated with increased ice production under dampened hydraulic conditions. Analysis of ice cores and drone footage highlights the role of skim ice runs in early cover formation, while predictions of skim ice formation show agreement with ice floe taxonomy from the literature. Establishing a baseline of freeze-up conditions for the region will assist in the development of predictive tools, such as numerical models, to optimize flow control decisions for this significant hydropower system. [ABSTRACT FROM AUTHOR]

Global climate change is expected to impact hydrodynamic conditions in stream ecosystems. There is limited understanding of how stream ecosystems interact and possibly adapt to novel hydrodynamic conditions. Combining mathematical modelling with field data, we demonstrate that bio-physical feedback between plant growth and flow redistribution triggers spatial self-organization of in-channel vegetation that buffers for changed hydrological conditions. The interplay of vegetation growth and hydrodynamics results in a spatial separation of the stream into densely vegetated, low-flow zones divided by unvegetated channels of higher flow velocities. This self-organization process decouples both local flow velocities and water levels from the forcing effect of changing stream discharge. Field data from two lowland, baseflow-dominated streams support model predictions and highlight two important stream-level emergent properties: vegetation controls flow conveyance in fast-flowing channels throughout the annual growth cycle, and this buffering of discharge variations maintains water depths and wetted habitat for the stream community. Our results provide important evidence of how plant-driven self-organization allows stream ecosystems to adapt to changing hydrological conditions, maintaining suitable hydrodynamic conditions to support high biodiversity. [ABSTRACT FROM AUTHOR]

Vegetation growth along rivers may have effects on water resistance and velocity distribution. Roughness evaluation is crucial in constructing river stage-discharge curves, due to its great importance in river management and risk assessment. Usually, land managers mechanically remove vegetation to increase flow conveyance and reduce flooding risk, with negative effects on the riverine ecosystem and hydraulic risk downstream. The study aims to implement a useful methodology for management planning along vegetated riparian zones through the development evaluation of both unmanaged and anthropically disturbed riparian ecosystems, using tree stands quantitative parameters required to estimate roughness caused by riparian vegetation. For each watercourse, it was also possible to evaluate the equivalent roughness dependent on river morphology and the effective flow resistance over time. The outputs of vegetation parameters analysis also may provide practical support in gentle maintenance interventions of Tuscan watercourses planning, to ensure positive effects both on water flow and on riverine ecosystem. [ABSTRACT FROM AUTHOR]

Shallow mixing layers developed in partially-distributed canopy flows (PCFs) are important for water conveyance, sediment transport and solute dispersion. In this paper, we address the response of shallow mixing layers in PCFs to several influential factors associated with bed friction, water shallowness and canopy denseness using depth-averaged Large Eddy Simulation (DA-LES). The results show that under certain canopy denseness, shallow mixing layers in PCFs display asymptotic behaviour for the variation of bed friction and water shallowness, consistent with classic shallow mixing layers. The canopy drag encourages the asymmetric growth of the inner and outer parts of the mixing layer, and this effect decreases when bed friction and water shallowness become pronounced. Characteristic velocity and length scales show similarity well delineated by exponential decay function regarding a stabilization efficiency parameter. The exception happens for the inner length scale of the mixing layer when only changing canopy density. We conclude that changing the canopy denseness can encourage the overall shift of mixing layer scaling regarding a broad range of bed friction and water shallowness. Furthermore, the bed friction parameter thresholding triggering flow instability of mixing layers in PCFs is found about 0.03, lower than 0.09 for splitter-plate induced mixing layers. [ABSTRACT FROM AUTHOR]

Irrigation and drainage engineering encompasses the human-made supply of water as well as the artificial drainage of excess water. A basic feature of many historical and modern irrigation and drainage systems has been the integrated use of hydraulic structures, most often low-head structures. These structures play a key role in water storage, conveyance, flow control and measurement, and energy dissipation. Yet, most systems are often designed assuming relatively simplistic design flow conditions. In this contribution, a number of relevant key challenges for hydraulic structures used in irrigation and drainage systems are discussed, using the operation of minimum energy loss weirs, the nonlinear behaviors of circular-crested weirs and the instabilities in fish-friendly box culverts equipped with sidewall baffles as examples. Altogether, the design approach of many hydraulic structures needs a rethink, far beyond the naive optimization for simplistic design flow conditions, with a greater focus on the safe and efficient operation across a broad range of less-than-design discharges, to be embedded in the design optimization approach. [ABSTRACT FROM AUTHOR]

Due to climate change, the frequency and intensity of torrential rainfall in urban areas are increasing, leading to more frequent flood damage. Consequently, there is a need for a rapid and accurate analysis of urban flood response capabilities. The dual-drainage model has been widely used for accurate flood analysis, with minimum time step synchronization being commonly adopted. However, this method has limitations in terms of speed. This study applied the hyper-connected solution for an urban flood (HC-SURF) model with fixed-time step flow synchronization, validated its accuracy using laboratory observation data, and tested its effectiveness in real urban watersheds with various synchronization times. Excellent performance was achieved in simulating real phenomena. In actual urban watersheds, as the synchronization time increased, the errors in surcharge and discharge also increased due to the inability to accurately reflect water level changes within the synchronization time; however, overall, they remained minimal. Therefore, the HC-SURF model is demonstrated as a useful tool for urban flood management that can be used to advantage in real-time flood forecasting and decision-making. [ABSTRACT FROM AUTHOR]

Here we investigate fluid flow in 90-degree bends with and without orifice-like constrictions. The results of flow in non-constricted bends were compared with experimental results for similar Reynolds numbers and found to be in good agreement. Calculations were then carried out for various Reynolds numbers in the laminar and turbulent regimes. In addition, constrictions up to a 60% blockage were incorporated. The present study shows that the Reynolds number and the presence of an orifice-like constriction affects the velocity profile and the pressure distribution. The results indicate that if a sudden contraction is encountered, the peak velocity is larger and the flow is more predisposed to the outer wall than it otherwise would be. In addition, a sudden contraction increases the pressure loss compared to the constant-area bend and it affects the pressure distribution throughout the entire bend. This paper provides a means to predict pressure losses (similar to minor loss coefficients) in rounded bends in the presence or absence of constrictions. Such information is important to practicing engineers for designing fluid-flow conveyance systems. The behavior of the fluid is shown to be connected to the constriction and is also affected by the Reynolds number. [ABSTRACT FROM AUTHOR]

Weird horizontal shapes of branches, in large branching estuaries, often cause significant flood risks and environment-related problems. People usually resort to engineering methods to improve the horizontal shape of the weird branches and solve related issues. The responses of the riverbed evolution of a branching estuary to anthropogenic activity are complicated because of complex estuarine hydrodynamics and sediment transports, especially when the project locates specially (e.g., at estuary outlets). The North Branch of the Yangtze Estuary has a narrow upper reach which is almost orthogonal to the South Branch and has a trumpet-shaped lower reach with a wide outlet. The weird horizontal shape of the North Branch brings significant flood risks to cities along this branch, the shrinkage of its entrance, and other problems. In this study, a regulation of the North Branch, which is launched at Guyuan Sand (GYS) just outside the exit of the North Branch, is taken as an example. The GYS regulation aims to improve the weird horizontal shape of the North Branch by building new layouts of outlets, by which people decrease the flood risk of the surrounding cities. The GYS regulation is studied using a 2D numerical model. The riverbed evolution of the Yangtze Estuary in a typical hydrological year is simulated, while the water/sediment fluxes at cross-sections of branches in the estuary during a spring/neap tide are quantitatively calculated. It is found that the regulation changes the rotational flows near the shore, and further reshapes the estuarine circulations of mass inside the outlets, especially exchanges of water/sediment between different branches. The regulation directly changes the riverbed evolution at the outlet of the North Branch, and meanwhile has significant indirect influences on the riverbed evolution of the entrance of the North Branch. The varying riverbed evolution at the entrance of the North Branch and the varying water/sediment fluxes, under different designs of regulations, are related and analyzed. An essential improvement for the weird horizontal shape of the North Branch by an engineering method is shown to be possible, while the regulation mechanism of the engineering method and the response of estuarine riverbed evolution to the regulation are clarified. This study provides a new insight for improving estuarine branches with weird horizontal shapes, by reshaping the tidal processes and the accompanying sediment transports in a branching estuary. [ABSTRACT FROM AUTHOR]

Silt removal is crucial for maintaining navigable waterways in harbors. Jet pumps, without moving parts, are highly suitable for underwater operations such as channel dredging in port environments. Despite their structural advantages in slurry handling, the prolonged transport of solid–liquid two-phase flows can lead to wear on the wall materials, resulting in decreased efficiency and potential pump failure. The wear characteristics of the jet pump walls due to sand particles of varying grain sizes were experimentally investigated. The characteristic of the sands having a higher distribution above the axis as they enter the jet pump was captured by a high-speed camera. The experiment recorded the variations in mass loss at different sections of the jet pump over a period of 120 h, identifying that backflow within the throat region is a significant contributor to wall wear. Scanning electron microscopy was employed to examine the microstructure of the abraded pump surfaces. It was found that there are noticeable differences in the surface wear microstructure across various pump areas, and that particles of different grain sizes result in distinct wear patterns on the pump surfaces. The underlying causes of this phenomenon were discussed from the perspective of particle motion. [ABSTRACT FROM AUTHOR]

In recent times, the demand for innovative, insignificantly invasive diagnostic and therapeutic biomedical tools has reached enhanced attention. Rapid Diagnostic Tests (RDTs) for diagnosis, which are non-invasive, inexpensive, simple, and deliver results accurately in less than 20 minutes, have heightened the accessibility to parasite-based analysis globally. Microneedle (MN) arrays are a fast-developing and promising technology for drug delivery and extraction of Interstitial fluid (ISF) employed for numerous diagnostic and clinical therapies. This review gives a broad overview of the characteristics and history of Microneedles (MNs) patches together with their applications in drug delivery and transdermal rapid diagnostic purposes, classifications, and categories based on the design of fabrication from previous works of literature spanning the period 2018-2023. Utilizing PubMed, Scopus, Google Scholar, and Wiley online library search engines, an online search for scientific publications published between 2018 and 2023 was conducted using the keywords "microneedle patch" and "rapid diagnostic tests." 175 articles in all were found when the search terms were used. The acquired results were then narrowed to 64 citations in this review by applying the inclusion principle. Pictorial and tabular representations highlight the various features of Microneedle patches used in interstitial fluid testing and extraction that have been documented experimentally, including numerous applications of Microneedle patches, showing their dimensions, applications, fabrication methods, and findings made. Finally, research on bio-microneedles and bio-inspired MN are reviewed. The research findings indicate that dissolving microneedles has become increasingly popular since they have several benefits over other microneedles. It is among the most well-known microneedles, and since it degrades naturally, it is a superior option for diagnosis and long-term treatment. [ABSTRACT FROM AUTHOR]

Enhanced understanding of flow resistance in open channels with emergent vegetation is essential for flood management and river ecosystem restoration. The presence of vegetation can significantly alter bed resistance, leading to a challenge in accurately predicting flow discharge, water levels, sediment transport, and bed deformation. Previous studies on vegetated flows have focused on vegetation resistance, on which the impact of vegetation has been ignored or poorly estimated. This study proposes a new analytical model, built upon the momentum conservation law, to predict flow resistance to vegetated zones in a plain bed without bed forms, explicitly quantifying bed resistance and vegetation resistance in a corollary manner. The proposed model is benchmarked against five typical sets of laboratory experiments. It is demonstrated that the present model using a modified logarithmic velocity distribution performs best, whereas that assuming a uniform velocity profile considerably overestimates the vegetation resistance and neglects the effect of vegetation on bed resistance. The ratio of bed resistance to the total resistance is shown to range between 5% and 40%, and it decreases with increasing vegetation density and decreases with water depth. Therefore, bed resistance cannot be ignored when modelling shallow water flow with sparsely distributed vegetation. It is also revealed that vegetation arrangements significantly affect flow resistance, and therefore a model incorporating the effect of vegetation arrangement performs better. Overall, the present model facilitates a viable and promising tool for quantifying flow resistance in emergent vegetated channels. [ABSTRACT FROM AUTHOR]

As green infrastructure has evolved, grass swales have become integral components of stormwater management. Manning's equation is commonly used to describe the hydraulic characteristics of grass swales. However, due to flow loss from infiltration, grass swales often deviate from the assumptions of Manning's equation, potentially leading to significant errors in grass swale flow rate calculations. In this study, we systematically investigated changes in flow rates in grass swales under various constant inflow rate conditions. The results indicated that the suitability of using Manning's equation to estimate flow rate in grass swales varies with inflow rate. At an inflow rate of 3.00 m3/h, the discrepancy between the measured and the estimated flow rates by Manning's equation was the smallest, ranging from −0.24 to 0.19 m3/h. At lower inflow rates (1.00 to 2.00 m3/h), Manning's equation underestimated the flow rates by 0.16 to 0.47 m3/h; at higher rates (4.00 m3/h), it overestimated the flow rates by 0.01 to 0.61 m3/h. Considering infiltration losses as the primary cause of these errors, we proposed an improved Darcy's formula for estimating the infiltration rates in grass swales, along with a modified Manning's equation for more accurate flow rate calculations. The modified Manning's equation provides enhanced accuracy in calculating flow rates in grass swales compared to the traditional version. [ABSTRACT FROM AUTHOR]

A paramount determinant in the selection of irrigation canal overflow configurations resides in their flow conveyance capacity. This overflow capacity is contingent upon the effective length and geometric characteristics of the weir. In the present investigation, the hydraulic performance and discharge coefficient (Cd) of circular-crested weir were scrutinized through the utilization of FLUENT software. Specifically, the study delved into the impact of geometric parameters, namely the radius and height of the crest, on these hydraulic aspects. Following the execution of calibration and validation procedures using FLUENT in conjunction with laboratory-derived data, the outcomes of the simulation revealed that augmenting the radius of the crest led to a corresponding escalation of 144.28% in the maximum pressure exerted on the crest and a 6.84% increase in flow depth. Conversely, the maximum velocity and Cd experienced reductions of 6.84% and 7.82%, respectively. The elevation of the weir height exhibited negligible influence on the maximum pressure magnitude at the crest. Contrastingly, a reduction in weir height constricted the range of pressure variations on the crest, indicating a more limited domain of pressure changes. Elevating the weir height induces a notable augmentation in the maximum flow velocity at the crest by 44.36%, concomitant with a reduction in both the depth and Cd by 52.66% and 68.96%, respectively.

Urban floods caused by extreme rainstorm events have increased in recent decades, particularly in concave-down bridge zones. To simulate urban flooding processes accurately, an integrated urban flood model (IUFM) was constructed by coupling a distributed urban surface runoff model based on the cellular automata framework (CA-DUSRM), a widely used pipe convergence module in the storm water management model (SWMM), with an inundation module that describes the overflow expansion process associated with terrain and land-cover. The IUFM was used in a case study of the Anhua Bridge (a typical concave-down overpass) study area in Beijing, China. The spatial-temporal variations in flood depth modeled by the IUFM were verified to be reliable by comparison with actual measurements and other simulations. The validated IUFM was used to obtain temporal variations in flood range, depth, and volume under four rainstorm scenarios (return periods of 3-year, 10-year, 50-year, and 100-year). The results showed that the surface runoff process, overflow from drainage networks, and overflow expansion process could affect the flooding status by changing the composition and spatial configuration of pervious or impervious patches, drainage capacity, and underlying surface characteristics (such as terrain and land-cover). Overall, although the simulation results from the IUFM contain uncertainties from the model structures and inputs, the IUFM is an effective tool that can provide accurate and timely information to prevent and control urban flood disasters and provide decision-making support for long-term storm water management and sponge city construction. [ABSTRACT FROM AUTHOR]