Hydraulic Environments Research Articles

Mixing processes and hydraulic environments in coastal regions: Internal tides and mixing phenomena

沿岸域における物質輸送過程は陸域と外洋間の物質収支の把握に重要であり，物質輸送過程の解明には混合現象の調査が必要不可欠である。本稿では，筆者がこれまでに行なってきた沿岸域における内部潮汐により発生する混合現象と関連する物質輸送に関する観測的研究や，数値計算を用いた内部潮汐のモデル化について紹介する。沿岸海域における混合現象はスケールが小さく直接詳細な構造を計測することが難しいことを着眼点に曳航式の観測装置を開発し，河口周辺における河川プリュームの混合状態や非線形性内部潮汐が斜面上で砕波する様子を観測することに成功した。大槌湾で観測した内部潮汐の砕波は，強い乱流混合による底質の巻き上げと中層高濁度層の形成を伴っていた。緩斜面においては，非線形性内部波の引き波と次の波が斜面上で衝突することで強い混合を発生させることを海洋の直接観測から始めて明らかにした。さらに内部潮汐の砕波を再現するモデルを開発し，内部潮汐砕波の詳細な構造の評価を行なった。また大スケールの海洋モデルを用いて，伊豆諸島周辺において日周期の内部潮汐が島々にトラップされ共振することで強化されることや，黒潮と内部潮汐の相互作用により黒潮上流方向への強い内部波エネルギーの伝播が起こることを発見した。本稿では，筆者が近年海洋観測技術を応用した湖沼における混合状態の研究事例も紹介する。

Influence of Complex Hydraulic Environments on the Mechanical Properties of Pile-Soil Composite Foundation in the Coastal Soft Soil Area of Zhuhai

Based on a plain concrete pile composite foundation project in the coastal area of Zhuhai, considering the complex hydraulic load environment induced by tidal water-level changes, finite element simulations and parameter calibrations were carried out to determine the physical and mechanical properties of plain concrete pile composite foundation. The hardening soil small (HSS) model, which can be used to simulate the complex mechanical behavior of soft soil under small strain, was selected for modeling analysis. Model parameters were calibrated through resonance column tests, triaxial consolidation drainage loading and unloading shear tests. The complex hydraulic loads were analyzed, including the effects of cyclic tidal action and the sudden rise and fall of the water level induced by strong storm surges on the force, deformation of plain concrete piles, and the mechanical seepage properties of soft soil around piles. The results indicate that: (1) Compared with coastal soft soil in Shanghai, Zhoushan, Tianjin, and other areas, the soft soil in the Zhuhai area has a smaller dynamic shear modulus, cohesion and internal friction angle, and worse engineering properties. (2) The sudden rise of water level leads to a sudden change in the pore pressure of the groundwater, which induces a large deformation of the pile-soil composite foundation. If the foundation on the offshore (dike) side exhibits the most prominent deformation and foundation damage, such as uneven settlement is prone to occur. (3) The offshore side pile is most affected by the hydraulic loads. The deformation of the pile body along the pile body is uneven and the deformation of the upper pile body is relatively large, which may cause fracture damage.

Plants and water: the search for a comprehensive understanding.

We learn early in life sciences classes that water is the solution of life, working in tandem with carbon to make life as we know it possible. Globally, the abundance of water can be misleading, as most of this water is unavailable, being overly salinized in the oceans or locked in deep underground reserves. On land, the critical supply is of freshwater, which is unevenly distributed in space and time. Even the wettest environments can experience episodic water deficit, and flash flooding periodically occurs in arid landscapes. While humanity can capture, store and transport freshwater over large distances to ensure sustained supply, such options are not apparent for plants except in an immediate local context. Plants must make do with the water in their immediate surroundings, whether it be abundant or scarce. How they do this has led to a myriad of adaptive solutions, involving capturing, storing and transporting water. The traits that enable them to optimize water use in a range of hydraulic environments, subject to multivariate selective constraints, are the essence of the discipline of plant-water relations.

A micromechanical framework for thermo-elastic properties of multiphase cementitious composites with different saturation

• A micromechanical framework is devised for thermo-elastic properties of CC . • The framework accurately predicts the thermo-elastic properties of CC. • Increasing saturation degree improves the thermo-elastic properties of CC. • CTE monotonically increases with the increase of porosity. Abstract: Understanding of the thermo-elastic properties of cementitious composites (CC) with different saturation degrees is of great importance for the design of CC durability in various hydraulic environments. This work devises a generic micromechanical framework to predict the effective thermo-elastic properties involving the elastic modulus, thermal conductivity, and coefficient of thermal expansion (CTE) of multiphase CC with different saturation degrees, composed of spheroidal aggregates and their surrounding interfacial transition zones (ITZs), water-pores, air-pores and homogeneous bulk paste at a microscopic scale. Comparisons against experimental measurements and theoretical bounds suggest that the micromechanical framework is a reliable means to accurately estimate the effective thermo-elastic properties of multiphase CC under different saturation conditions. The proposed model sheds light on the quantitative effects of saturation degree, porosity, pore shape, and aggregate shape and volume fraction, and ITZ thickness on the thermo-elastic properties of CC, which can provide insights for the design of “tailor-to-demand” thermo-elasticity performance of CC.

Confined Cell Migration and Asymmetric Hydraulic Environments to Evaluate the Metastatic Potential of Cancer Cells.

Metastasis, a hallmark of cancer development, is also the leading reason for most cancer-related deaths. Furthermore, cancer cells are highly adaptable to micro-environments and can migrate along pre-existing channel-like tracks of anatomical structures. However, more representative three-dimensional models are required to reproduce the heterogeneity of metastatic cell migration in vivo to further understand the metastasis mechanism and develop novel therapeutic strategies against it. Here, we designed and fabricated different microfluidic-based devices that recreate confined migration and diverse environments with asymmetric hydraulic resistances. Our results show different migratory potential between metastatic and nonmetastatic cancer cells in confined environments. Moreover, although nonmetastatic cells have not been tested against barotaxis due to their low migration capacity, metastatic cells present an enhanced preference to migrate through the lowest resistance path, being sensitive to barotaxis. This device, approaching the study of metastasis capability based on confined cell migration and barotactic cell decisions, may pave the way for the implementation of such technology to determine and screen the metastatic potential of certain cancer cells.

Friction factor evaluation in tidal rivers and estuaries

The Saint-Venant equations are usually used for simulation of unsteady flow in various hydraulic environments including tidal estuaries and adjacent river sections called tidal rivers. These equations form the basis of most contemporary one-dimensional hydrodynamic models. Unlike lowland rivers, tidal rivers are characterized by the high variability of hydraulic resistance during a tidal cycle. The rapid variation in hydrodynamic conditions reflects changes in the ratio of forces responsible for the water movement (gravity, inertia, friction). The expression and the parametrization of the flow resistance for the unsteady currents usually are the same as for the uniform flows. As a result, the friction slope can be calculated as the hydraulic gradient from Chezy, Chezy-Manning or Darcy–Weisbach equations. The proposed method was developed to measure, calculate and analyze the variation of the friction factor in tidal rivers and estuaries characterized by reverse flow.•The method allows to identify the range of every term in the Saint-Venant momentum equation and to evaluate the contribution of different forces causing water movement during a tidal cycle.•The experimental evaluation of the friction factor and the range of its variation is a key point for accurate hydrodynamic modeling of tidal rivers.

Research influence of biological corrosion on the strength of steel structures of hydrotechnical construction of long-term operation in aggressive environments

Biocorrosion is caused by the vital activity of various microorganisms that use metals as a nutrient medium or produce products that destroy metal structures. Anaerobic is the most dangerous (growth without oxygen) sulfate-reducing bacteria, which are present in slimy and swamp soils. Bacteria restore sulfate ions to sulfides ions, accelerating corrosion of metal. Life of aerobic bacteria occurs only in the presence of oxygen. Bacteria oxidize sulfur to sulfuric acid, the concentration of which in separate places can reach 10%. Ironobacteria absorb iron in ionic form and excrete it in the form of non-dissolved compounds. Since non-dissolved products are distributed on the metal surface unevenly, the electrochemical heterogeneity of the surface occurs, which accelerates corrosion. Microorganisms formed on the metal surface can cause not only corrosion. They can also increase the concentration of hydrogen sulfide in the environment by increasing the amount of deposits on steel hydraulic structures.
 The greatest danger from the point of view of corrosion is sulfate reducing bacteria (SRB), which are widespread in hydraulic environments. Sulfate renewable bacteria belong to the class of anaerobic bacteria, the vital activity of which can be without oxygen. Aerobic bacteria, such as ironbacteria (IB) and sulfur bacteria or thionic (TB), which are present in groundwater with SRB, is viable only in the presence of oxygen. Anaerobic and aerobic bacteria have a common existence environment, and therefore often the development of one species creates favorable conditions for others.

Spatio-temporal distribution of Gymnocypris przewalskii during migration with UAV-based photogrammetry and deep neural network

The naked carp (Gymnocypris przewalskii) plays a central role in the ecosystem of the Qinghai Lake, the largest saline-alkaline lake in China. The adult naked carp migrates in large groups with high population density annually from the Qinghai Lake to the upstream freshwater rivers to spawn. Nevertheless, the responsiveness of the fish to local abiotic cues in the form of distribution patterns during migration across the riverine-lacustrine network of the Qinghai Lake region remains unknown. This knowledge gap has reduced efficiency in fish conservation and management efforts in the region. To address this issue, we carried out two field surveys from June to August, 2018, with the aid of unmanned aerial vehicles to a 200-m long back channel characterizing diverse morphological and hydraulic features on the migration route. Combined structure from motion photogrammetry and deep neural network techniques were used to establish a new workflow for detecting and extracting the profiles of fish individuals in large schools. The spatio-temporal distribution pattern of the fish demonstrated that the naked carp was attracted by hydraulic environments with high flow velocity or deep-water during migration. The diurnal variation of temperature and light could alter the preference for hydraulic environments of the fish. Our results highlight the crucial role of the interactions between river morphology and hydraulics, water temperature and light on the migration behaviours of the naked carp.

Effects of flow-interruption on the bacteria transport behavior in porous media

Attachment is an important strategy for microorganisms to survive, grow, and perform biogeochemical functions in soil and groundwater systems. This study investigated the effect of flow-interruption (FI) that is common in subsurface environments on bacterial attachment/detachment using a metal-reducing bacterium Shewanella oneidensis strain (MR1) as an example. Column experiments and one dimensional bacterial transport models were performed by varying flow interruption duration, fluid ionic strength, and solid grain surface electrostatic properties with a goal to understand the effect of FI on bacterial attachment/detachment. The results indicated that MR1 generally behaved as colloidal particles in transport and attachment/detachment under continuous flow conditions. However, the FI events induced a significant release of MR1 in both injection and elution phases, showing a peak MR1 concentration, which was higher than that in the injecting solution, immediately after the FI events. The peak MR1 concentrations were higher in systems with lower adhesive forces between bacteria and solid grains, a lower attachment site capacity in porous media, and a longer FI duration. The diffusive release of the previously attached bacteria during the FI events and the momentum force when flow re-started immediately after the FI events were likely the mechanisms leading to bursting release of bacteria with the release concentrations higher than that in the influent solutions. The results have important implication for understanding bacterial migration and attachment, and their subsequent functions, especially in dynamic hydraulic environments such as in hyporheic zones or in soils subject to dynamic changes in infiltration rates under for example extreme precipitation and drought conditions.

Frictional characteristics of thin-walled tubes in liquid impact forming

PurposeThis paper aims to study frictional characteristics of thin-walled tubes in the liquid impact forming (LIF) process.Design/methodology/approachLIF experiments under various impacting velocities were performed on SUS304 stainless steel tubes with various guiding lengths on a custom-designed measurement system to investigate the effects of impacting velocity and guiding length on the coefficient of friction (COF) in the guiding zone.FindingsThe results indicate that the COF changes dynamically in the guiding zone and decreases with the deformation process. The reduction range of the COF is wider in LIF than in both the conventional and pulsating hydroforming (THF), which may be contributed to the impacting velocities in a short time. Moreover, the COF decreases faster in the first half of the LIF process than in the second half. Under different impacting velocities and guiding lengths, the decreasing rate of the COF in the first half is more sensitive and obvious than that in the second half.Originality/valueA method for determining the COF in the guiding zone in LIF is proposed and the frictional characteristics in LIF are studied. Comparing the COF of tubes in conventional THF, pulsating THF and the LIF process is valuable for improving and predicting the tubular formability in various hydraulic environments for industrial production.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2019-0269

Quantitative response of riverine benthic invertebrates to sediment grain size and shear stress

The most widespread pressure impacting river ecological status is the degradation of key hydromorphologic elements, such as sediment type and flow rate. However, almost nothing is known about the quantitative relationship between benthic invertebrate abundance and these elements. This synthesis compiles quantitative data on physical requirements and thresholds for invertebrates relative to two hydromorphologic factors: substrate size and hydraulic energy (measured as shear stress). Both factors are commonly a focus of river rehabilitation. However, we found only limited literature data that we could use to identify invertebrate preferences (189 taxa). Preferred substrate sizes of all stream epifauna we examined varied between 0.05 and 400 mm and they prefer shear stresses from 0.13 to 3.67 N m−2. There was no difference in variation of preferred conditions between the examined taxonomic levels. We suspect that taxa preferring hydraulic environments with shear stresses < 0.64 N m−2 are affected more by environmental factors than solely being constrained by substrate or hydraulic energy preferences. Such taxa might be useful as sensitive indicator species for evaluating stream integrity. Hence, to optimize restoration success for riverine biota, hydromorphological forces should be mitigated by manipulating habitat complexity in a way that it enhances intact ecological processes.

Friction stir processing of dual certified 304/304L austenitic stainless steel for improved cavitation erosion resistance

Cavitation erosion is known to be prevalent in equipment in hydraulic environments. Understanding cavitation erosion and improving the erosion resistance of commonly used materials is of interest for both scientific and economic reasons. In this study, friction stir processing was employed to modify commercial dual certified AISI 304/304L austenitic stainless steel plates. The cavitation erosion behavior of the processed plates was evaluated and compared to that of the unprocessed steel. A temperature control algorithm was employed to maintain a target tool temperature during the processing. The cross sections of the processed nuggets were evaluated using optical microscopy, scanning electron microscopy and Vickers hardness testing. Erosion testing by cavitation liquid jet was performed conforming to ASTM G134 on specimens cut out of the nuggets of the commercially unprocessed and the processed 304/304L steel. The tool temperature was found to affect the microstructure and the cavitation erosion behavior. Friction stir processed steel showed greater than 3× improvement in cavitation erosion resistance (defined as the reciprocal of the mass loss of a given material) than the unprocessed 304/304L. Surface erosion patterns and erosion rates were characterized and the mechanisms of material removal were discussed.

Flood energy dissipation in anabranching channels

AbstractThis study examines the character of developing anabranched channel networks on the River Wear, north England, using metre‐scale aerial LiDAR. DSM‐DTM interpretation reveals a well‐developed vegetation structure and a locally diverse terrain, dominated by an interlinked channel network split by low‐elevation depositional areas with the gross morphology of the reach resembling that of a strongly active meandering/wandering channel suggesting that an anabranching network may develop within systems that were initially active meandering and wandering, evolving in line with floodplain vegetative succession. Utilization of the LiDAR DEM in the hydrological component of the CAESAR‐Lisflood (version 1.4) morphodynamic model has generated local hydraulic variable estimates through the anabranched reaches for a range of flows. These data clearly demonstrate how elevated flows are transferred out of the primary channel and distributed along the interconnected secondary channel network, creating a diverse set of hydraulic environments. Areas between the channels rapidly become inundated as flows increase, dissipating flow energy. Shear stress estimates throughout the study site reveal a generally reduced ability to mobilize sediments and erode channel margins, in comparison with a single‐thread reach immediately downstream. Anabranched secondary channels appear to operate in disequilibrium and act predominantly as aggradational zones, although with some evidence of scour at channel bifurcation and confluence points. It would appear that the topographic character of anabranching sites efficiently manages flood flow energy, activating secondary channels and low‐elevation areas to distribute flood flows. These findings contrast with the hydraulic data from an adjacent single‐thread reach, characterized by flood flows concentrated in‐channel creating a high erosive potential. We propose that anabranching rivers could play an important role in natural flood and sediment management in many U.K. river systems.

An Investigation of the Bacterial Influence of Acidithiobacillus Thiooxidans on Concrete Composites

Vegetation and microorganisms present the biological factors that deteriorate concrete. These problems are very visible in places like sewage, underground and hydraulic structures, chemical plants, industrial structures, liquid-containing structures, agricultural structures or marine environments. The most significant biodeteriogens are the sulphur-oxidising bacteria Acidithiobacillus thiooxidans (A. thiooxidans) and the sulphatereducing bacteria (Desulfovibrio spp.) that are responsible for the so-called sulphuretum consortium. Microorganisms that produce sulphuric acid accelerate the deterioration of concrete sewer pipes in a process termed Microbially Induced Concrete Corrosion (MIC). The paper considers the assessment of the release of calcium and silicon from concrete composites with and without coal fly ash by sulphur-oxidizing bacteria. The concrete mixture contained coal fly ash as 5 wt. % and wt. 10 % cement replacement. Prepared composites were exposed to an aggressive microbial environment under laboratory conditions for 3 months. The pH values were measured and studied during this time period. A different resistance against MIC was observed for the concrete composites of different compositions. The highest amount of calcium leached-out from the concrete was in the case of the composites where 10 % cement was replaced by fly ash.

Trophic and halieutic dynamics of grazer–predator fishes: harvesting optimal control policies for the environmental sustainability and bioeconomic cases

Interactions between trophic and halieutic populations, have often been ignored in most mathematical models that are interested in prey–predator dynamics. However, the presence of vegetation in hydraulic environments, is important, and it has a direct impact on the life cycle of many fishes. In fact, aquatic populations are essential for providing oxygen, food and also shelter for grazers. For this, we suggest a mathematical and optimization approach, in an attempt to discuss the possibility of finding effective harvesting control strategies that aim to optimize the fishing efforts without affecting the trophic-halieutic populations and compromising with the interests of fishermen. The model is in the form of three ordinary differential equations, and which describes dynamics of multi-species of a fishery that includes grazer–predator fishes and aquatic plants, during fishing periods. We study the stability of the proposed differential system, and we suggest harvesting optimal control approaches for the environmental sustainability and bioeconomic cases after the introduction of two control functions in the model and which represent the efforts of fishing in grazer and predator populations respectively. The two optimal controls are characterized in the first case, based on Pontryagin’s maximum principle, and we seek their analytical formulations in the second case, when they are singular functions. Hence, these two optimal control approaches lead to two two-point boundary value problems which are resolve numerically based on the forward-backward sweep method with the incorporation of iterative Runge-Kutta fourth order progressive-regressive schemes.

Attached biofilms and suspended aggregates are distinct microbial lifestyles emanating from differing hydraulics.

Small-scale hydraulics affects microbial behaviour at the cell level1, trophic interactions in marine aggregates2 and the physical structure and function of stream biofilms3,4. However, it remains unclear how hydraulics, predictably changing from small streams to large rivers, impacts the structure and biodiversity of complex microbial communities in these ecosystems. Here, we present experimental evidence unveiling hydraulics as a hitherto poorly recognized control of microbial lifestyle differentiation in fluvial ecosystems. Exposing planktonic source communities from stream and floodplain ecosystems to different hydraulic environments revealed strong selective hydraulic pressures but only minor founder effects on the differentiation of attached biofilms and suspended aggregates and their biodiversity dynamics. Key taxa with a coherent phylogenetic underpinning drove this differentiation. Only a few resident and phylogenetically related taxa formed the backbone of biofilm communities, whereas numerous resident taxa characterized aggregate communities. Our findings unveil fundamental differences between biofilms and aggregates and build the basis for a mechanistic understanding of how hydraulics drives the distribution of microbial diversity along the fluvial continuum5-7.

Historical and contemporary waterscapes of North Australia: Indigenous attitudes to dams and water diversions

Indigenous engagements with water are dynamic and contextually contingent, and contemporary attitudes and environmental valuations are shaped by diverse pre-existing water histories. Geographical variation intersects and interacts with such histories to influence the moral position taken by individuals and groups and their negotiating positions as they engage in public debates or decisions about water diversion, management, and use, as well as the tradeoffs and risks of associated negative impacts. This paper draws together Indigenous historical and contemporary perspectives regarding the diversion, damming and manipulation of water sources from four tropical watersheds that span Australia’s remote north—the Harding and Ord Rivers in Western Australia, the Roper River in the Northern Territory, and the Gilbert River in North Queensland. Conceptually, the paper brings together the literatures of Indigenous water values and the political ecology of water resources. The analysis deploys the waterscape concept that has emerged from the disciplines of geography and history to characterise the key features of Indigenous peoples’ dynamic relationships to water and to link water and social power relations in these watersheds over time. The cases support the proposition that Indigenous people are often concerned about industrial-scale water diversion and damming. Yet our regional studies also undercut the notion that such concerns emerge from an Indigenous culture that passively responds to the prevailing hydrology, or the idea popular in settler Australia that these hydraulic environments are themselves unaffected by past human action. Indigenous attitudes to diversion and damming are informed by previous experiences of water manipulation, which include the social relations that shaped these practices, at times with demonstrably pre-colonial origins, as well as by contemporary perspectives on the tradeoffs between development, sustainable local livelihoods, and environmental and cultural impact. Our analysis of the Australian context informs ongoing international debates about large scale irrigated agriculture, aquaculture, mining, and other water-intensive development in regions occupied by Indigenous peoples and experiencing high and increasing water variability.

Weakening laws of rock uniaxial compressive strength with consideration of water content and rock porosity

Laboratory compressive experiments are regarded as the most accurate method to obtain the strength parameters of rock, and the rocks used for experiments are often dry. However, in geotechnical engineering, the rock masses are often under different hydraulic environments because of which rock strength decreases by varying degrees; consequently, there are considerable differences between laboratory results and engineering practices. Research on the quantitative relationships between rock strength and water content would contribute to the application of laboratory results to engineering practice and can become the basis for engineering rock mass stability analysis and forecasting. On the basis of 14 different groups of rock strength data with different water contents, statistical and numerical methods are used to obtain the least squares fit relationship between rock strength and water content, and the fitting results demonstrate that sandstone strength and water content have a negative exponential relationship. Meanwhile, through parameter analysis, we obtain the physical meaning of each parameter in the three-parameter exponential fitting curves, thus establishing the laws that govern the weakening of rock uniaxial compressive strength. The newly established model takes the rock porosity and water content into account, and the rock strength at a certain water content can be computed according to the experimentally obtained rock strength in dry and completely water-saturated conditions, as well as the rock porosity. The model has been validated by two case studies using comparative analysis between theoretical values and experimental data.

Cavitation Erosion of Cermet-Coated Aluminium Bronzes.

The cavitation erosion resistance of CuAl10Ni5Fe2.5Mn1 following plasma spraying with Al2O3·30(Ni20Al) powder and laser re-melting was analyzed in view of possible improvements of the lifetime of components used in hydraulic environments. The cavitation erosion resistance was substantially improved compared with the one of the base material. The thickness of the re-melted layer was in the range of several hundred micrometers, with a surface microhardness increasing from 250 to 420 HV 0.2. Compositional, structural, and microstructural explorations showed that the microstructure of the re-melted and homogenized layer, consisting of a cubic Al2O3 matrix with dispersed Ni-based solid solution is associated with the hardness increase and consequently with the improvement of the cavitation erosion resistance.

A 100 μm diameter capacitive pressure sensor with 50 MPa dynamic range

This paper presents fully sealed absolute capacitive pressure sensors for high-pressure applications in hydraulic environments. The sensors have a ø100 μm diaphragm and a nominal interelectrode gap of 3 μm. The interiors of the cavities are electrically isolated, allowing the sensors to operate at the high end of the pressure range with the center of the diaphragm in contact with the substrate beneath it. The sensors are monolithically fabricated using a combination of surface micromachining and through-wafer isolated bulk-silicon lead transfer for backside contacts. This structure allows the device footprints to be reduced to about 150 × 150 μm2, and simplifies system integration. Fabricated sensors with diaphragm thicknesses of 3 μm (C100t3) and 5 μm (C100t5) are tested in an oil environment at pressures up to 20 MPa and 50 MPa, respectively. The average sensitivities are 7200 ppm MPa−1 (3.1 fF MPa−1) for C100t3, and 3400 ppm MPa−1 (1.6 fF MPa−1) for C100t5 in the non-contact mode. In the contact mode, the average sensitivities are 9900 ppm MPa−1 (5.3 fF MPa−1) for C100t3, and 3100 ppm MPa−1 (1.6 fF MPa−1) for C100t5. A multiphysics finite element analysis approach that accommodates contact mode simulations is also presented.