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1
Beal, Cara D., Ted Gardner, David W. Rassam, Alison M. Vieritz, and Neal W. Menzies. "Effluent flux prediction in variably saturated soil zones within a septic tank—soil absorption trench." Soil Research 44, no. 7 (2006): 677. http://dx.doi.org/10.1071/sr06007.
Повний текст джерелаАнотація:
The treatment and hydraulic mechanisms in a septic tank–soil absorption system (SAS) are highly influenced by the clogging layer or biomat zone which develops on bottom and lower sidewall surfaces within the trench. Flow rates through the biomat and sub-biomat zones are governed largely by the biomat hydraulic properties (resistance and hydraulic conductivity) and the unsaturated hydraulic conductivity of the underlying soil. One- and 2-dimensional models were used to investigate the relative importance of sidewall and vertical flow rates and pathways in SAS. Results of 1-dimensional modelling show that several orders of magnitude variation in saturated hydraulic conductivity (Ks) reduce to a 1 order of magnitude variation in long-term flow rates. To increase the reliability of prediction of septic trench hydrology, HYDRUS-2D was used to model 2-dimensional flow. In the permeable soils, under high trench loading, effluent preferentially flowed in the upper region of the trench where no resistant biomat was present (the exfiltration zone). By comparison, flow was more evenly partitioned between the biomat zones and the exfiltration zones of the low permeability soil. An increase in effluent infiltration corresponded with a greater availability of exfiltration zone, rather than a lower resistance of biomat. Results of modelling simulations demonstrated the important role that a permeable A horizon may play in limiting surface surcharge of effluent under high trench hydraulic loading.
2
Tannant, D. D., P. K. Kaiser, and D. H. Chan. "Effect of tunnel excavation on transmissivity distributions and flow in a fracture zone." Canadian Geotechnical Journal 30, no. 1 (February 1, 1993): 155–69. http://dx.doi.org/10.1139/t93-014.
Повний текст джерелаАнотація:
During an excavation-response experiment performed at the Underground Research Laboratory (Atomic Energy of Canada Limited, Pinawa, Man.) a decrease in fracture-zone transmissivity was measured as a tunnel intersected the room 209 fracture zone. The decrease in transmissivity was greatest as the pilot and the slash faces passed the fracture zone. The transmissivities increased towards their preexcavation values as the faces proceeded past the fracture zone. This response suggested that shear stresses or displacements controlled the hydraulic behaviour of the fractures. The hydraulic response in the fracture zone was analyzed using finite element models. Predictions of shear-displacement distributions in the fracture zone as a function of face position were obtained from a three-dimensional finite element model using joint elements to represent the fracture zone. A phenomenological relationship between shear displacement and transmissivity change was used to modify the transmissivity distributions in the fracture zone based on shear displacements for different excavation stages. Seepage analyses with these transmissivities provided predictions that matched closely the field measurements obtained from the room 209 fracture zone. These results and the inability of conventional, normal stress dependent, fracture closure to predict consistently the hydraulic response support the concept of shear causing a reduction in fracture-zone transmissivity. Excavation-dependent, shear-induced reduction in transmissivity provides an alternate mechanism for interpreting and understanding the hydraulic response of disturbed fracture zones. Key words : transmissivity, shear displacement, fluid flow, fracture zone, excavation.
3
Tannant, D. D., and P. K. Kaiser. "A shear-dependent fracture-zone transmissivity model." Canadian Geotechnical Journal 30, no. 1 (February 1, 1993): 146–54. http://dx.doi.org/10.1139/t93-013.
Повний текст джерелаАнотація:
Shear displacements caused by excavation through a fracture zone can decrease the overall fracture-zone transmissivity. The complex arrangement of flow channels found in fracture zones creates a situation where imposed shear displacements will reduce the aperture of critically oriented fractures. This paper presents a simple flow model based on the en echelon structure found in many fracture zones from which a phenomenological relationship between shear displacement and transmissivity change is established. This model is then used to demonstrate the effect of shear displacement around a circular opening. The effects of shear-induced decreases in transmissivity are most dramatic when a continuous low-transmissivity zone is created around the opening. In this case, the steady-state heads can be relatively high and the resulting hydraulic gradient into the excavation can be extremely large. If the low-transmissivity zone around the opening is discontinuous because, for example, the shear displacements are nonaxisymmetric, then the inflow becomes channelled and the steady-state heads and hydraulic gradients near the excavation substantially decrease. The concept of shear-induced transmissivity reduction in fracture zones provides an alternative mechanism to shear-induced dilation and normal stress induced fracture closure for interpreting and explaining the observed hydraulic response in fracture zones. Key words : transmissivity, shear displacement, fluid flow, en echelon fractures, fracture zone, excavation.
4
Pozdniakov, S. P., N. E. Sizov, and V. A. Lekhov. "THE SIZE OF THE SANITARY PROTECTION ZONE OF THE WATER INTAKE WELL IN THE LAYERED HETEROGENEOUS AQUIFER." Engineering Geology World 14, no. 2 (September 3, 2019): 74–81. http://dx.doi.org/10.25296/1993-5056-2019-14-2-74-81.
Повний текст джерелаАнотація:
Sanitary protection zones (SPZ) of water intakes allocate on the time of movement from the outer boundary of the zone to the water intakes. For example, for zone II it is the time of microbial contamination transport, accepted for target aquifers insufficiently protected from the surface, which is equal to 400 days. For zone III, this is the time of chemical pollution transport equal to the estimated lifetime of the water intake. To calculate the spatial position of the boundaries of these zones, analytical and numerical methods are used based on the integration of equations for the velocities of neutral particles in the groundwater flow, the flow field of which formed by the superposition of the natural flow velocities and the disturbances imposed on it by groundwater abstraction. When these methods are used, the only configuration of the sanitary protection zone that corresponds to some homogeneous or heterogeneous spatial field of hydraulic parameters obtained from field materials and (or) from the solution of the inverse problem is obtained as a result of calculations. At the same time, possible variations of SPZ boundaries are not considered due to local hydraulic heterogeneity, which is not taken into account in the water intake model. The article analyzes the influence of vertical hydraulic heterogeneity on the formation of sanitary protection zones in the layered heterogeneous aquifer. Random stationary fields of normally distributed logarithms of hydraulic conductivity were used as a basis for the model of hydraulic heterogeneity. As a result, the sizes of the first and second zones of sanitary protection were estimated and the comparative analysis of the received values with the sizes of SPZ was carried out, which were determined without taking into account model hydraulic heterogeneity. The analysis showed that the consideration of model hydraulic heterogeneity leads to a significant increase in the sanitary protection zones.
5
Rose-Harvey, Keisha, Kevin J. McInnes, and James C. Thomas. "Water Flow Through Sand-based Root Zones Atop Geotextiles." HortScience 47, no. 10 (October 2012): 1543–47. http://dx.doi.org/10.21273/hortsci.47.10.1543.
Повний текст джерелаАнотація:
An alternative to the time-tested gravel drainage layer beneath a sand-based root zone of a sports field or golf putting green can be constructed from a geotextile atop a highly porous drainage material or structure. The geotextile serves to support the root zone mixture on the drainage layer whose pores can be too large for the sand to support itself by bridging. In such an application, the geotextile should have high enough strength and resistance to stretching to support the root zone mixture atop the pores of the drainage layer and should contain internal pores of appropriate size to retain the bulk of particles in the root zone mixture and to allow free passage of drainage water and eluviating fine particles. The objective of this study was to determine whether geotextiles selected to meet these criteria affect the drainage rates of sand-based root zones and whether they affect the size of particles lost from the root zone–geotextile systems. In a 1-year laboratory study that made use of 150-mm diameter polyvinyl chloride (PVC) test cells, measurements of drainage rates and saturated hydraulic conductivities were made on replicated combinations of 10 geotextiles and three 300-mm deep root zone mixtures. Size distributions and total masses of particles that passed from the root zones through the geotextiles were measured. Statistical analyses showed that drainage rate, saturated hydraulic conductivity, and size distribution and mass of eluviated particles were unaffected by the properties of the geotextiles. The results gave of no reason to prohibit the use of geotextiles to support sand-based root zones in golf putting greens or sports fields.
6
Pagnozzi, Mauro, Gianluca Coletta, Guido Leone, Vittorio Catani, Libera Esposito, and Francesco Fiorillo. "A Steady-State Model to Simulate Groundwater Flow in Unconfined Aquifer." Applied Sciences 10, no. 8 (April 14, 2020): 2708. http://dx.doi.org/10.3390/app10082708.
Повний текст джерелаАнотація:
The hydraulic and hydrogeological features of the Caposele aquifer have been investigated by using a numerical groundwater flow model. In particular, groundwater flow simulations were performed for a multilayered, unconfined aquifer in steady-state conditions for different thicknesses of the aquifer’s saturated zone. The Caposele groundwater model was carried out starting from a generic model drained by a unique spring outlet in accordance with the geo-hydrological features of the study area. The conceptual model was built considering hydrogeological features of spring catchment, and was then implemented with the MODFLOW numerical code. A combined 2D-3D approach was adopted, and the model was calibrated on borehole data available for the time period 2012–2019. Different thicknesses of the aquifer were set, and a reliable relationship was found between the hydraulic head, saturated zone and hydraulic conductivity of the aquifer. Using the MODPATH package, the mean travel time (Darcian) of groundwater was computed for five different scenarios, corresponding to the model’s depths; the analysis that was performed shows that the travel time is higher for a greater and lower for a smaller thickness of the aquifer’s saturated zone, respectively. The Caposele aquifer model was zoned in different sectors, named flow pipe areas, that play different roles in groundwater recharge-discharge processes. A vector analysis was also carried out in order to highlight the ascendant flow near the spring zone.
7
Dethier, David P., Noah Williams, and Jordan F. Fields. "Snowmelt-Driven Seasonal Infiltration and Flow in the Upper Critical Zone, Niwot Ridge (Colorado), USA." Water 14, no. 15 (July 26, 2022): 2317. http://dx.doi.org/10.3390/w14152317.
Повний текст джерелаАнотація:
The hydrology of alpine and subalpine areas in the Colorado Front Range (USA) is evolving, driven by warming and by the alteration of precipitation patterns, the timing of snowmelt, and other components of the hydrologic budget. Field measurements of soil hydraulic conductivity and moisture along 30-m transects (n = 13) of representative soils developed in surficial deposits and falling head slug tests of shallow groundwater in till demonstrate that hydraulic conductivity in the soil is comparable to hydraulic conductivity values in the shallow aquifer. Soil hydraulic conductivity values were variable (medians ranged from 5.6 × 10−7 to 4.96 × 10−5 m s−1) and increased in alpine areas underlain by periglacial deposits. Hydraulic conductivities measured by a modified Hvorslev technique in test wells ranged from 4.86 × 10−7 to 1.77 × 10−4 m s−1 in subalpine till. The results suggest a gradient from higher hydraulic conductivity in alpine zones, where short travel paths through periglacial deposits support ephemeral streams and wetlands, to lower hydraulic conductivity in the till-mantled subalpine zone. In drier downstream areas, streambed infiltration contributes substantially to near-channel groundwater. As summer temperatures and evapotranspiration (ET) increase and snowmelt occur earlier, alpine soils are likely to become more vulnerable to drought, and groundwater levels in the critical zone may lower, affecting the connectivity between late-melting snow, meltwater streams, and the areas they affect downstream.
8
Ranieri, E. "Hydraulics of sub-superficial flow constructed wetlands in semi arid climate conditions." Water Science and Technology 47, no. 7-8 (April 1, 2003): 49–55. http://dx.doi.org/10.2166/wst.2003.0670.
Повний текст джерелаАнотація:
This paper reports the evaluation of the hydraulics of two constructed wetland (cws) plants located in Apulia (the South Eastern Italy region characterized by semi arid climate conditions). These fields were planted with Phragmites australis hydrophytes and are supplied with local secondary wastewater municipal treatment plant effluent. Each plant - Kickuth Root-Zone method based - covers an area of approx. 2,000 m2. The evapotranspiration phenomenon has been evaluated within perforated tubes fixed to the field bottom and very high values - up to 40 mm/d - were found. Hydraulic conductivity has been evaluated by in situ measurements at different field points. Hydraulic gradients and the piezometric curve within the field are also reported.
9
Luo, Can, Hao Liu, Li Cheng, Chuan Wang, Weixuan Jiao, and Di Zhang. "Unsteady Flow Process in Mixed Waterjet Propulsion Pumps with Nozzle Based on Computational Fluid Dynamics." Processes 7, no. 12 (December 3, 2019): 910. http://dx.doi.org/10.3390/pr7120910.
Повний текст джерелаАнотація:
The unsteady flow process of waterjet pumps is related to the comprehensive performance and phenomenon of rotating stall and cavitation. To analyze the unsteady flow process on the unsteady condition, a computational domain containing nozzle, impeller, outlet guide vane (OGV), and shaft is established. The surface vortex of the blade is unstable at the valley point of the hydraulic unstable zone. The vortex core and morphological characteristics of the vortex will change in a small range with time. The flow of the best efficiency point and the start point of the hydraulic unstable zone on each turbo surface is relatively stable. At the valley point of the hydraulic unstable zone, the flow and pressure fields are unstable, which causes the flow on each turbo surface to change with time. The hydraulic performance parameters are measured by establishing the double cycle test loop of a waterjet propulsion device compared with numerical simulated data. The verification results show that the numerical simulation method is credible. In this paper, the outcome is helpful to comprehend the unsteady flow mechanism in the pump of waterjet propulsion devices, and improve and benefit their design and comprehensive performance.
10
Peng, Li, Wang Kai, Li Bo, Jiang Yifeng, and Gou Jianqiang. "Research on the Effective Influence Radius of Hydraulic Reaming in Mining Seam." Open Fuels & Energy Science Journal 8, no. 1 (July 31, 2015): 161–67. http://dx.doi.org/10.2174/1876973x01508010161.
Повний текст джерелаАнотація:
In Accordance with the present situations suggesting that the construction of the gas drainage boreholes in mining seam is sufficient and the gas drainage effect in low permeability coal seams does not yield perfectly, the hydraulic reaming technology in mining seam was proposed to increase the gas drainage efficiency. Through the gas flow method, the effective influence radius of hydraulic reaming was determined and the fluid-solid coupling model of gas drainage along boreholes after hydraulic reaming was established theoretically. Following this, the changes in the laws of gas content around the boreholes in the coal seam were simulated and analyzed. The results indicated that hydraulic reaming can effectively promote the stress-relief and permeability-increase of the coal mass around the boreholes, and the coal mass around the reaming boreholes can be divided into gas flow increase zone, gas flow delay attenuation zone and fast decay zone. The effective influence radius of hydraulic reaming was 5.5~6 m. The obtained simulation results were basically in accordance with the field investigation.
11
Ni, C. F., C. P. Lin, S. G. Li, and J. S. Chen. "Quantifying flow and remediation zone uncertainties for partially opened wells in heterogeneous aquifers." Hydrology and Earth System Sciences 15, no. 7 (July 18, 2011): 2291–301. http://dx.doi.org/10.5194/hess-15-2291-2011.
Повний текст джерелаАнотація:
Abstract. This study presents a numerical first-order spectral model to quantify transient flow and remediation zone uncertainties for partially opened wells in heterogeneous aquifers. Taking advantages of spectral theories in solving unmodeled small-scale variability in hydraulic conductivity (K), the presented nonstationary spectral method (NSM) can efficiently estimate flow uncertainties, including hydraulic heads and Darcy velocities in r- and z-directions in a cylindrical coordinate system. The velocity uncertainties associated with the particle backward tracking algorithm are then used to estimate stochastic remediation zones for scenarios with partially opened well screens. In this study the flow and remediation zone uncertainties obtained by NSM were first compared with those obtained by Monte Carlo simulations (MCS). A layered aquifer with different geometric mean of K and screen locations was then illustrated with the developed NSM. To compare NSM flow and remediation zone uncertainties with those of MCS, three different small-scale K variances and correlation lengths were considered for illustration purpose. The MCS remediation zones for different degrees of heterogeneity were presented with the uncertainty clouds obtained by 200 equally likely MCS realizations. Results of simulations reveal that the first-order NSM solutions agree well with those of MCS for partially opened wells. The flow uncertainties obtained by using NSM and MCS show identically for aquifers with small ln K variances and correlation lengths. Based on the test examples, the remediation zone uncertainties (bandwidths) are not sensitive to the changes of small-scale ln K correlation lengths. However, the increases of remediation zone uncertainties (i.e. the uncertainty bandwidths) are significant with the increases of small-scale ln K variances. The largest displacement uncertainties may have several meters of differences when the ln K variances increase from 0.1 to 1.0. Such conclusions are also valid for the estimations of remediation zones in layered aquifers.
12
Ni, C. F., C. P. Lin, S. G. Li, and J. S. Chen. "Quantifying flow and remediation zone uncertainties for partially opened wells in heterogeneous aquifers." Hydrology and Earth System Sciences Discussions 8, no. 2 (March 30, 2011): 3133–66. http://dx.doi.org/10.5194/hessd-8-3133-2011.
Повний текст джерелаАнотація:
Abstract. This study presents a numerical first-order spectral model to quantify flow and remediation zone uncertainties for partially opened wells in heterogeneous aquifers. Taking advantages of spectral theories in solving unmodeled small-scale variability in hydraulic conductivity (K), the presented nonstationary spectral method (NSM) can efficiently estimate flow uncertainties, including hydraulic heads and Darcy velocities in r- and z profile in a cylindrical coordinate system. The velocity uncertainties associated with the particle backward tracking algorithm are then used to estimate stochastic remediation zones for scenarios with partially opened well screens. In this study the flow and remediation zone uncertainties obtained by NSM were first compared with those obtained by Monte Carlo simulations (MCS). A layered aquifer with different geometric mean of K and screen locations was then illustrated with the developed NSM. To compare NSM flow and remediation zone uncertainties with those of MCS, three different small-scale K variances and correlation lengths were considered for illustration purpose. The MCS remediation zones for different degrees of heterogeneity were presented with the uncertainty clouds obtained by 200 equally likely MCS realizations. Results of simulations reveal that the first-order NSM solutions agree well with those of MCS for partially opened wells. The flow uncertainties obtained by using NSM and MCS show identically for aquifers with small ln K variances and correlation lengths. Based on the test examples, the remediation zone uncertainties are not sensitive to the changes of small-scale ln K correlation lengths. However, the increases of remediation zone uncertainties are significant with the increases of small-scale ln K variances. The largest displacement uncertainties may have several meters of differences when the ln K variances increase from 0.1 to 1.0. Such results are also valid for the estimations of remediation zones in layered aquifers.
13
Zuikov, Andrey L., and Elena V. Bazhina. "Viscous stress tensor and stability of laminar contravortical flows." Vestnik MGSU, no. 7 (July 2019): 870–84. http://dx.doi.org/10.22227/1997-0935.2019.7.870-884.
Повний текст джерелаАнотація:
Introduction: coaxial layers in contravortical flows rotate in the opposite directions. This determines their complicated spatial structure. The relevance of the subject is in the uniquely effective mixing of the moving medium. This property has a great potential of application from microbiology and missile building for obtaining highly dispersed mixtures to heat engineering for increasing the intensity of heat transfer. However, contravortical flows have a high degree of hydrodynamic instability. This hinders effective development of these technologies. Contravortical flows are observed behind Francis hydroturbines, whose derated operation causes modes with a significant increase of hydraulic unit vibrations up to destruction of the units. The purpose of the study is to identify physical laws of the contravortical flow hydrodynamics, common for both laminar and turbulent fluid flow modes.
Materials and methods: theoretical analysis of the viscous stress tensor and local stability zones of contravortical laminar flows.
Results: the article provides a mathematical description of the tensor of viscous tangential (τij) and normal (σii) stresses as well as local stability zones of the flow according to Rayleigh (Ra) and Richardson (Ri) criteria. The graphs of the radial-axial distributions of the viscous stress components are given, local stability zones are shown and the point of “vortex breakdown” is indicated. The solutions are obtained in the form of Fourier – Bessel series. The hydrodynamic structure of the flow is analysed.
Conclusions: it is established that the most significant viscous stresses are observed at the beginning of the interaction zone of contrarotating layers. It is established that the areas with the most unstable flow are localized in the flow vortex core. Three zones can be distinguished in the vortex core: a zone of weak instability with local Richardson numbers to Ri = –1, passing into a zone of flow destabilization with high negative values of Richardson numbers Ri = –10 to –100, in turn, transforming into a zone with rapidly increasing instability up to Ri = –1000. This is a zone of loss of flow stability, culminating in the “ortex breakdown”.
14
Zhu, Lin, Huili Gong, Zhenxue Dai, Gaoxuan Guo, and Pietro Teatini. "Modeling 3-D permeability distribution in alluvial fans using facies architecture and geophysical acquisitions." Hydrology and Earth System Sciences 21, no. 2 (February 3, 2017): 721–33. http://dx.doi.org/10.5194/hess-21-721-2017.
Повний текст джерелаАнотація:
Abstract. Alluvial fans are highly heterogeneous in hydraulic properties due to complex depositional processes, which make it difficult to characterize the spatial distribution of the hydraulic conductivity (K). An original methodology is developed to identify the spatial statistical parameters (mean, variance, correlation range) of the hydraulic conductivity in a three-dimensional (3-D) setting by using geological and geophysical data. More specifically, a large number of inexpensive vertical electric soundings are integrated with a facies model developed from borehole lithologic data to simulate the log10(K) continuous distributions in multiple-zone heterogeneous alluvial megafans. The Chaobai River alluvial fan in the Beijing Plain, China, is used as an example to test the proposed approach. Due to the non-stationary property of the K distribution in the alluvial fan, a multiple-zone parameterization approach is applied to analyze the conductivity statistical properties of different hydrofacies in the various zones. The composite variance in each zone is computed to describe the evolution of the conductivity along the flow direction. Consistently with the scales of the sedimentary transport energy, the results show that conductivity variances of fine sand, medium-coarse sand, and gravel decrease from the upper (zone 1) to the lower (zone 3) portion along the flow direction. In zone 1, sediments were moved by higher-energy flooding, which induces poor sorting and larger conductivity variances. The composite variance confirms this feature with statistically different facies from zone 1 to zone 3. The results of this study provide insights to improve our understanding on conductivity heterogeneity and a method for characterizing the spatial distribution of K in alluvial fans.
15
Abed, Adnan Ajam, and Sammer Mohammed Hamd-Allah. "Comparative Permeability Estimation Method and Identification of Rock Types using Cluster Analysis from Well Logs and Core Analysis Data in Tertiary Carbonate Reservoir-Khabaz Oil Field." Journal of Engineering 25, no. 12 (November 21, 2019): 49–61. http://dx.doi.org/10.31026/j.eng.2019.12.04.
Повний текст джерелаАнотація:
Characterization of the heterogonous reservoir is complex representation and evaluation of petrophysical properties and application of the relationships between porosity-permeability within the framework of hydraulic flow units is used to estimate permeability in un-cored wells. Techniques of flow unit or hydraulic flow unit (HFU) divided the reservoir into zones laterally and vertically which can be managed and control fluid flow within flow unit and considerably is entirely different with other flow units through reservoir. Each flow unit can be distinguished by applying the relationships of flow zone indicator (FZI) method. Supporting the relationship between porosity and permeability by using flow zone indictor is carried out for evaluating the reservoir quality and identification of flow unit used in reservoir zonation. In this study, flow zone indicator has been used to identify five layers belonging to Tertiary reservoirs. Consequently, the porosity-permeability cross plot has been done depending on FZI values as groups and for each group denoted to reservoir rock types. On the other hand, extending rock type identification in un-cored wells should apply a cluster analysis approach by using well logs data. Reservoir zonation has been achieved by cluster analysis approach and for each group known as cluster which variation and different with others. Five clusters generated in this study and permeability estimated depend on these groups in un-cored wells by using well log data that gives good results compared with different empirical methods.
16
Xu, Wei Sheng. "Study on the Influence of Variable Water Temperature on Seepage in Single Fracture." Applied Mechanics and Materials 405-408 (September 2013): 358–62. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.358.
Повний текст джерелаАнотація:
approximate analysis formula for the water flow of single fracture and variable water temperature has been deduced considering the impact of water temperature to rock fracture seepage. Following conclusions were drawn: (1) The water head and the hydraulic gradient in single-fissure have nonlinear relation. Seepage curve was convex curve if water flows from higher temperature areas to lower temperature area. On this condition, the water head slants low under liner seepage simplification. On the contrary, Seepage curve is convex curve if water flows from lower temperature areas to higher temperature areas, and the water head slants high. (2) In a single fracture, the hydraulic gradient is smaller in the higher temperature zone and is larger in the lower temperature zone. The higher the mean water temperature of fracture was, and the faster the flow velocity was.
17
Smith, M., and J. M. Konrad. "Analysis of the annual thermal response of an earth dam for the assessment of the hydraulic conductivity of its compacted till core." Canadian Geotechnical Journal 45, no. 2 (February 2008): 185–95. http://dx.doi.org/10.1139/t07-095.
Повний текст джерелаАнотація:
Heat carried by the seepage water along hydraulic flow lines can serve as a natural tracer to help detect contrasting hydraulic conductivities in embankment dams. Thermal monitoring was realized on the 94.5 m high QA-01 embankment dam in northern Quebec to characterize the temperature distribution across its entire section. The analysis of the annual thermal response of the dam clearly showed a zone of higher seepage velocities in the compacted till core. Approximations concerning the increased hydraulic conductivity were made using a simple thermal model. Complementary numerical modelling provided a more rigorous quantitative assessment of the seepage patterns. The calculations have shown hydraulic conductivities that are 20 times larger than the expected values. Thermal monitoring can detect zones of increased seepage, which can be related to internal erosion or other factors, such as the variability of the soil properties due to construction practices. Temperature measurements alone are not adequate to determine the cause of a permeable zone in a dam or to predict its possible evolution.
18
Simi, Anne L., and Cynthia A. Mitchell. "Design and Hydraulic Performance of a Constructed Wetland Treating Oil Refinery Wastewater." Water Science and Technology 40, no. 3 (August 1, 1999): 301–7. http://dx.doi.org/10.2166/wst.1999.0175.
Повний текст джерелаАнотація:
This paper considers the hydraulics of a wetland constructed by BP Oil for polishing wastewater from their oil refinery at Bulwer Island, Australia. As this open water surface flow (SF) wetland has a novel design to enhance mixing, a tracer study was performed to analyse the hydraulic flow distribution through the wetland. It is a baseline study, following construction, prior to planting. As introduction to the study, details of the wetland design are provided, together with design justification. The volume of the wetland active zone is estimated as 70% of the total wetland capacity, which compares very favourably with the active volume expected in flat-bottomed ponds. The large amount of dispersion observed along the length of the wetland bed approaches that of a well-mixed system, supporting the claim that this novel bed structure enhances mixing. We expect to at least retain, and possibly improve the degree of mixing by alternating planted shallow zones with unplanted deep zones. The first stage of experimental work at this wetland involves creating a baseline of hydraulic data on which to build a mass balance model of the wetlands performance. Tracer studies will be repeated on the planted, mature wetland to determine the changes to flow, which might occur in the operating system. Together with wetland performance results, these studies will underpin investigations into the pollutant removal mechanisms at BP Oil's Bulwer Island wetland.
19
Baimanov, Kenesbay, Gulmurat Shaniyazov, Torebek Uzakov, and Ruslan Baimanov. "Hydraulic resistances of suspended flows in bedrooms with a moving bottom." E3S Web of Conferences 264 (2021): 03017. http://dx.doi.org/10.1051/e3sconf/202126403017.
Повний текст джерелаАнотація:
The results of some existing theoretical and experimental studies of hydraulic resistances of open flows in moving channels are considered. Possible reasons for the inconsistency of the results of various studies of hydraulic resistance in open channels with increased roughness are indicated. The analysis of mass field data on the Darcy (Shezi) coefficient of canals in alluvial soils and a sandy mobile bed is carried out. It was confirmed that the channels of these categories are characterized by a mixed zone of hydraulic resistance, and regularities were revealed that take into account the features of the real resistance zone of earthen channels. Based on the analysis of the smoothly varying flow of open flows and the corresponding theory of the boundary layer and the law of the logarithmic distribution of velocities, the calculated dependencies are obtained, making it possible to determine the resistance of open flows concerning natural conditions.
20
Deininger, Andrea, Frank W. Günthert, and Peter A. Wilderer. "The influence of currents on circular secondary clarifier performance and design." Water Science and Technology 34, no. 3-4 (August 1, 1996): 405–12. http://dx.doi.org/10.2166/wst.1996.0457.
Повний текст джерелаАнотація:
Density currents in the deeper zones of clarifiers and currents in the clear water zone have a significant influence on clarifier performance. Measurements of flow velocity profiles were conducted in full-scale horizontally flown circular secondary clarifiers. Relations between the hydraulic load and the development of density currents could be detected. Those patterns are not taken into account in current design procedures. Stationary design approaches are mainly based on the overflow rate. Novel design methods based on the dynamic behavior of flow and density distribution in clarifiers are needed in order to improve the efficacy of wastewater treatment systems.
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Meng, Xin, Yubao Zhou, Zhilin Sun, Kaixuan Ding, and Lin Chong. "Hydraulic Characteristics of Emerged Rigid and Submerged Flexible Vegetations in the Riparian Zone." Water 13, no. 8 (April 12, 2021): 1057. http://dx.doi.org/10.3390/w13081057.
Повний текст джерелаАнотація:
Flow resistance, velocity distribution, and turbulence intensity are significantly influenced by aquatic vegetations (AV) in riparian zones. Understanding the hydraulics of flow with planted floodplains is of great significance for determining the velocity distribution profile and supporting the fluvial processes management. However, the traditional flume experiment method is inefficient. Therefore, the multigroup simultaneous flume test method was carried out to describe the flow patterns affected by emerged rigid (reed and wooden stick) and submerged flexible vegetations (grass and chlorella). The Acoustic Doppler Velocimeter (ADV) was utilized to measure the velocity at one point for different experimental conditions. The results showed that hydraulic features were influenced by different types of vegetation. Furthermore, the relative depth (z/h) was a determining factor of those variations. In addition, the time-averaged velocity distributions of planted floodplains are not logarithmic. Instead, they represented “s-shape” profiles. In detail, for the vegetated floodplains, reed and wood followed an s-shape profile, but for grass and chlorella, they followed reverse s-shape profile. For all cases, turbulence is not isotropic and the change law of turbulence intensity is different in different sections. The flow resistance, turbulence intensities, and Reynold stresses influenced by different types of vegetation were also analyzed.
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Gholami, Vahid. "Prediction of flood discharge and flood flow depth using a hydraulic model and flood marks on the trees in ungauged forested watersheds." Journal of Forest Science 68, No. 5 (May 26, 2022): 190–98. http://dx.doi.org/10.17221/6/2022-jfs.
Повний текст джерелаАнотація:
It is difficult to estimate flood discharges and the flood zones as well as to design hydraulic structures in rivers without using hydrometric stations. Furthermore, using different models to determine the mentioned cases will be accompanied by errors. Therefore, flood marks on the trunks of trees located in the Babolrood riverbed were used to determine the peak discharge, flood flow depth, and flood zone in northern Iran. First, a hydraulic model for the study river was provided using topographic maps with a scale of 1: 1 000, HEC-GeoRAS extension (GIS), and HEC-RAS model. Then, the flood marks of past floods in the form of silt and clay sediments (deposits on the trees in the riverbed) were evaluated and the maximum flood flow depth was determined. Finally, the peak discharge of the past flood was estimated by the trial-and-error method to achieve the flood flow depth in the different river reaches. Then, the hydraulic model using the flow depth data was calibrated in the reaches, and, in the final step, based on the flood marks of other reaches, the model was validated. According to the results, the maximum instantaneous discharge rate of the study flood was 155 m<sup>3</sup>·s<sup>–1</sup> and the maximum flood flow depth was about 2 m. Furthermore, the results showed that the flood mark data in forest lands can be used as a tool for the calibration and validation of hydraulic models. The present methodology is an efficient method for determining the flood peak discharge, spatial variation of the flood depth, and flood zone in forest watersheds without hydrometric stations.
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Williams, Howard. "Rethinking Wat’s Dyke: A Monument’s Flow in a Hydraulic Frontier Zone." Offa's Dyke Journal 3 (December 23, 2021): 151. http://dx.doi.org/10.23914/odj.v3i0.332.
Повний текст джерелаАнотація:
Britain’s second-longest early medieval monument – Wat’s Dyke – was a component of an early medieval hydraulic frontier zone rather than primarily serving as a symbol of power, a fixed territorial border or a military stop-line. Wat’s Dyke was not only created to monitor and control mobility over land, but specifically did so through its careful and strategic placement by linking, blocking and overlooking a range of watercourses and wetlands. By creating simplified comparative topographical maps of the key fluvial intersections and interactions of Wat’s Dyke for the first time, this article shows how the monument should not be understood as a discrete human-made entity, but as part of a landscape of flow over land and water, manipulating and managing anthropogenic and natural elements. Understanding Wat’s Dyke as part of a hydraulic frontier zone not only enhances appreciation of its integrated military, territorial, socio-economic and ideological functionality and significance, most likely the construction of the middle Anglo-Saxon kingdom of Mercia, it also theorises Wat’s Dyke as built to constitute and maintain control both across and along its line, and operating on multiple scales. Wat’s Dyke was built to manage localised, middle-range as well as long-distance mobilities via land and water through western Britain and beyond.
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Veras, Tatiane Barbosa, Jaime Joaquim da Silva Pereira Cabral, Anderson Luiz Ribeiro de Paiva, Roberto Lima Barcellos, and Laércio Leal dos Santos. "Vertical hydraulic gradient research in hyporheic zone of Beberibe river in Pernambuco State (Brazil)." RBRH 21, no. 4 (October 13, 2016): 674–84. http://dx.doi.org/10.1590/2318-0331.011615153.
Повний текст джерелаАнотація:
ABSTRACT The interaction between groundwater and surface water occurs naturally and is dependent on the dynamics in the hyporheic zone. The hyporheic zone is the interface between the surface water source and the phreatic aquifer and it’s a system that also influences the water quality. An important feature is the ability to flux in this zone. This work aimed to evaluate the vertical hydraulic gradient in the hyporheic zone at two points in Beberibe river, Olinda-PE, to understand the hyporheic environment characteristics and water flow dynamics in experimental area, in addition to identify the existence of hydraulic connection between surface water and groundwater. The experimental phase consisted of infiltration tests in riverbed with cylinder infiltrometer and vertical hydraulic gradients readings with differential piezometer, complemented with grain size information, for an assessment of the water budget between the river and the aquifer. Analyzing the behavior of the interaction over the period of 10 months, it was observed that the Beberibe river (middle course) contributes to the groundwater recharge in most of the time. The average infiltration rate was 1.02 mm/min in point 1 and 0.85 mm/min in point 2. It was concluded that there is a variability in flow direction, which often is top-down, but may undergo change in the stream showing upstream after long periods of rainfall. Another conclusion is that grain size distribution of bed sediment, that is predominantly sandy, influences hydraulic conductivity of hyporheic zone and influences consequently the vertical flow rates.
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Hou, Xiaokun, Sai K. Vanapalli, and Tonglu Li. "Water flow in unsaturated soils subjected to multiple infiltration events." Canadian Geotechnical Journal 57, no. 3 (March 2020): 366–76. http://dx.doi.org/10.1139/cgj-2018-0566.
Повний текст джерелаАнотація:
In this paper, water flow in a 4 m height column with an unsaturated soil that is subjected to multiple infiltration events for a 62 day period is investigated. One-dimensional (1D) numerical analysis is also undertaken to analyze the flow, extending the seepage theory for unsaturated soils. Results highlight the formation of two wetting fronts; namely, wetting front I and wetting front II that are induced by the first and subsequent infiltration events, respectively. There is a stable zone where the water content is approximately constant; it forms between the two fronts. A conceptual model of the suction profile is proposed for interpreting in situ water flow by dividing the unsaturated zone into four distinct zones; namely, active, steady, transition, and capillary fringe zones. This division is helpful for providing a rational explanation of water flow in different zones. Novel contributions from this study include a relationship between the hydraulic properties in the steady zone and the flow velocity, which is determined by an average influx rate. In addition, the rate of groundwater recharge can also be estimated using the average influx rate. Results of the present study are useful to understand and interpret the relationship between water infiltration and suction or water content profile in the unsaturated zone as well as variation of groundwater table level.
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Baehr, Arthur L., and Timothy J. Reilly. "Unsaturated Flow Characterization Utilizing Water Content Data Collected within the Capillary Fringe." Air, Soil and Water Research 7 (January 2014): ASWR.S13282. http://dx.doi.org/10.4137/aswr.s13282.
Повний текст джерелаАнотація:
An analysis is presented to determine unsaturated zone hydraulic parameters based on detailed water content profiles, which can be readily acquired during hydrological investigations. Core samples taken through the unsaturated zone allow for the acquisition of gravimetrically determined water content data as a function of elevation at 3 inch intervals. This dense spacing of data provides several measurements of the water content within the capillary fringe, which are utilized to determine capillary pressure function parameters via least-squares calibration. The water content data collected above the capillary fringe are used to calculate dimensionless flow as a function of elevation providing a snapshot characterization of flow through the unsaturated zone. The water content at a flow stagnation point provides an in situ estimate of specific yield. In situ determinations of capillary pressure function parameters utilizing this method, together with particle-size distributions, can provide a valuable supplement to data libraries of unsaturated zone hydraulic parameters. The method is illustrated using data collected from plots within an agricultural research facility in Wisconsin.
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Lancaster, Jill, and Alan G. Hildrew. "Characterizing In-stream Flow Refugia." Canadian Journal of Fisheries and Aquatic Sciences 50, no. 8 (August 1, 1993): 1663–75. http://dx.doi.org/10.1139/f93-187.
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Flow in nine streams was examined in relation to refugia for invertebrates. Areas of bed maintaining low hydraulic stress throughout the discharge hydrograph could provide flow refugia for animals during spates. In one stream, near-bed shear stress and velocity were repeatedly measured in discrete patches. Three types were identified: "fast" patches maintained high hydraulic stress, "variable" patches showed the greatest change in stress, and "slow" patches maintained low stress and thus were potential refugia. Average stress increased with discharge, but potential refugia were prominent throughout and could be important for invertebrates. Abundances of refugia in eight comparison streams were characterized by changes in the frequency distribution of flow forces with discharge. Three stream types were identified that did not simply reflect channel size or morphology. Such stream-specific flow patterns could affect the structure of comunities through the differing provision of refugia. Longitudinal transport processes in these streams were investigated by solute dilution experiments and by the application of a model to measure an aggregated "dead zone". Transport (and dead zone volume) varied among streams and further reflected their refuge potential. Clearly, flow habitat features could intervene in population and community dynamics by providing refuge from spates.
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Xue, J. Y., C. Z. Meng, X. F. Fan, Z. W. Wang, and L. J. Zhou. "Study on the characteristics of vortex motion and pressure pulsation in vaneless zone of Kaplan turbine." IOP Conference Series: Earth and Environmental Science 1037, no. 1 (June 1, 2022): 012005. http://dx.doi.org/10.1088/1755-1315/1037/1/012005.
Повний текст джерелаАнотація:
Abstract Kaplan turbine with adjustable blade has wide operating efficiency and is widely used in medium and low head hydropower stations. Pressure pulsation has always been a key problem affecting the operating efficiency and stability of hydraulic turbines. The numerical simulation of the hydraulic characteristics of Kaplan turbine is carried out to analyze the pressure pulsation and flow distribution characteristic in the vaneless zone under different guide vane openings and blade installation angles. Results show that: At the small flow condition, vortices appear in the vaneless zone, which leads to the increase of pressure pulsation in the vaneless zone and the expansion of the fluctuation range of water moment on blade. At the small flow condition with different unit speed, the dominant frequency are observed to be between 4-5 times rotation frequency in the vaneless zone far from the runner inlet. The frequency source is that the rotating vortex flow and the rotating runner blade will form the effect similar to rotor-stator interference.The pressure pulsation observed at the monitoring point near the runner inlet mainly comes from the disturbance of the runner blade to the flow and the pressure pulsation frequency is 6fn .
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Meshalkin, Valery P., Nicolay A. Martsulevich, Oleg M. Flisyuk, Ilia G. Likhachev, and Antony M. Nzioka. "Hydrodynamics of Energy-Efficient Axial-Flow Cyclones for Environmentally Safe Cleaning of Gas and Dust Emissions." Energies 16, no. 2 (January 10, 2023): 816. http://dx.doi.org/10.3390/en16020816.
Повний текст джерелаАнотація:
We investigated the operation of an axial-flow cyclone as the most promising dust-cleaning equipment based on energy consumption. Numerical solutions were obtained for the gas-solids suspension flow equations in axial flow cyclones with different separation chambers’ geometry using FlowVision software. The chamber’s geometrical features determined the nature of the gas-solids suspension flow, directly affecting the dusty gases’ purification degree. The circulating gas flows and the turbulent “trace” after the swirl generator were found to negatively influence the cyclone efficiency and the hydraulic resistance values. A high chamber height also negatively affected the gas purification since the bulk of dust particles were removed from the gas-solids flow at the initial section. The initial section’s length coincided with the gas-solids suspension’s jet flow zone due to the flow coming off the swirl vanes’ edges. Due to turbulent mixing, the particles’ secondary entrainment and return to the gas flow began to manifest outside this zone. Based on this analysis, it is possible to develop recommendations for choosing the chamber’s geometric parameters, minimizing the influence of the indicated factors. On the basis of this research, it will be possible to ensure cyclones’ high efficiency with significantly lower hydraulic resistance when designing axial-flow cyclones relative to other types of cyclone.
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Chen, Zhan Xiu, and Juan Men. "The Hydraulic Characteristics of Inner Loop Biological Fluidized Bed Set Ring-Type Baffle." Advanced Materials Research 807-809 (September 2013): 1147–50. http://dx.doi.org/10.4028/www.scientific.net/amr.807-809.1147.
Повний текст джерелаАнотація:
The flow field of the traditional inner loop biological fluidized bed reactor (ILBFBR) and a new biological fluidized bed reactor set ring-type baffle was calculated by computational fluid dynamics. The results show that the gas holdup of drop zone in ILBFBR set the ring-type baffle can increase significantly, the flow rate of drop zone in ILBFBR with the ring-type baffle is faster than that in traditional ILBFBR, and turbulence intensity distributed more evenly all in rising zone and drop zone in ILBFBR set the ring-type baffle than that in traditional ILBFBR, but static pressure difference of ILBFBR set ring-type baffle is higher than that of the traditional ILBFBR.
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Liu, Weitao, Jiyuan Zhao, Ruiai Nie, Yuben Liu, and Yanhui Du. "A Coupled Thermal-Hydraulic-Mechanical Nonlinear Model for Fault Water Inrush." Processes 6, no. 8 (August 7, 2018): 120. http://dx.doi.org/10.3390/pr6080120.
Повний текст джерелаАнотація:
A coupled thermal-nonlinear hydraulic-mechanical (THM) model for fault water inrush was carried out in this paper to study the water-rock-temperature interactions and predict the fault water inrush. First, the governing equations of the coupled THM model were established by coupling the particle transport equation, nonlinear flow equation, mechanical equation, and the heat transfer equation. Second, by setting different boundary conditions, the mechanical model, nonlinear hydraulic-mechanical (HM) coupling model, and the thermal-nonlinear hydraulic-mechanical (THM) coupling model were established, respectively. Finally, a numerical simulation of these models was established by using COMSOL Multiphysics. Results indicate that the nonlinear water flow equation could describe the nonlinear water flow process in the fractured zone of the fault. The mining stress and the water velocity had a great influence on the temperature of the fault zone. The temperature change of the fault zone can reflect the change of the seepage field in the fault and confined aquifer. This coupled THM model can provide a numerical simulation method to describe the coupled process of complex geological systems, which can be used to predict the fault water inrush induced by coal mining activities.
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Wang, Guangdong, Ailin Jia, Yunsheng Wei, and Cong Xiao. "Transient Pressure Analysis for Multifractured Horizontal Well with the Use of Multilinear Flow Model in Shale Gas Reservoir." Geofluids 2020 (February 7, 2020): 1–20. http://dx.doi.org/10.1155/2020/8348205.
Повний текст джерелаАнотація:
Shale gas reservoirs (SGR) have been a central supply of carbon hydrogen energy consumption and hence widely produced with the assistance of advanced hydraulic fracturing technologies. On the one hand, due to the inherent ultralow permeability and porosity, there is stress sensitivity in the reservoirs generally. On the other hand, hydraulic fractures and the stimulated reservoir volume (SRV) generated by the massive hydraulic fracturing operation have contrast properties with the original reservoirs. These two phenomena pose huge challenges in SGR transient pressure analysis. Limited works have been done to take the stress sensitivity and spatially varying permeability of the SRV zone into consideration simultaneously. This paper first idealizes the SGR to be four linear composite regions. What is more, the SRV zone is further divided into subsections on the basis of nonuniform distribution of proppant within the SRV zone which easily yields spatially varying permeability away from the main hydraulic fracture. By means of perturbation transformation and Laplace transformation, an analytical multilinear flow model (MLFM) is obtained and validated as a comparison with the previous models. The flow regimes are identified, and the sensitivity analysis of critical parameters is conducted to further understand the transient pressure behaviors. The research results provided by this work are of significance for an effective recovery of SGR resources.
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Wang, Huimin, J. G. Wang, Feng Gao, and Xiaolin Wang. "A Two-Phase Flowback Model for Multiscale Diffusion and Flow in Fractured Shale Gas Reservoirs." Geofluids 2018 (2018): 1–15. http://dx.doi.org/10.1155/2018/5910437.
Повний текст джерелаАнотація:
A shale gas reservoir is usually hydraulically fractured to enhance its gas production. When the injection of water-based fracturing fluid is stopped, a two-phase flowback is observed at the wellbore of the shale gas reservoir. So far, how this water production affects the long-term gas recovery of this fractured shale gas reservoir has not been clear. In this paper, a two-phase flowback model is developed with multiscale diffusion mechanisms. First, a fractured gas reservoir is divided into three zones: naturally fractured zone or matrix (zone 1), stimulated reservoir volume (SRV) or fractured zone (zone 2), and hydraulic fractures (zone 3). Second, a dual-porosity model is applied to zones 1 and 2, and the macroscale two-phase flow flowback is formulated in the fracture network in zones 2 and 3. Third, the gas exchange between fractures (fracture network) and matrix in zones 1 and 2 is described by a diffusion process. The interactions between microscale gas diffusion in matrix and macroscale flow in fracture network are incorporated in zones 1 and 2. This model is validated by two sets of field data. Finally, parametric study is conducted to explore key parameters which affect the short-term and long-term gas productions. It is found that the two-phase flowback and the flow consistency between matrix and fracture network have significant influences on cumulative gas production. The multiscale diffusion mechanisms in different zones should be carefully considered in the flowback model.
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Pastore, Nicola, Claudia Cherubini, and Concetta I. Giasi. "Kinematic diffusion approach to describe recharge phenomena in unsaturated fractured chalk." Journal of Hydrology and Hydromechanics 65, no. 3 (September 1, 2017): 287–96. http://dx.doi.org/10.1515/johh-2017-0033.
Повний текст джерелаАнотація:
AbstractWhen dealing with groundwater resources, a better knowledge of the hydrological processes governing flow in the unsaturated zone would improve the assessment of the natural aquifer recharge and its vulnerability to contamination. In North West Europe groundwater from unconfined chalk aquifers constitutes a major water resource, therefore the need for a good hydrological understanding of the chalk unsaturated zone is essential, as it is the main control for aquifer recharge. In the North Paris Basin, much of the recharge must pass through a regional chalk bed that is composed of a porous matrix with embedded fractures. The case study regards the role of the thick unsaturated zone of the Cretaceous chalk aquifer in Picardy (North of France) that controls the hydraulic response to rainfall. In order to describe the flow rate that reaches the water table, the kinematic diffusion theory has been applied that treats the unsaturated water flow equation as a wave equation composed of diffusive and gravitational components. The kinematic diffusion model has proved to be a convenient method to study groundwater recharge processes in that it was able to provide a satisfactory fitting both for rising and falling periods of water table fluctuation. It has also proved to give an answer to the question whether unsaturated flow can be described using the theory of kinematic waves. The answer to the question depends principally on the status of soil moisture. For higher values of hydraulic Peclet number (increasing saturation), the pressure wave velocities dominate and the preferential flow paths is provided by the shallow fractures in the vadose zone. With decreasing values of hydraulic Peclet number (increasing water tension), rapid wave velocities are mostly due to the diffusion of the flow wave. Diffusive phenomena are provided by matrix and fracture-matrix interaction.The use of a kinematic wave in this context constitutes a good simplified approach especially in cases when there is a lack of information concerning the hydraulic properties of the fractures/macropores close to saturation.
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Shen, Qi, Zhifang Zhou, Meng Chen, Sijia Li, Zhe Wang, and Yabing Li. "An Analytical Solution for Non-Darcian Flow on a Constant Head Packer Test in the Interlayer Staggered Zone." Geofluids 2021 (November 8, 2021): 1–13. http://dx.doi.org/10.1155/2021/7170769.
Повний текст джерелаАнотація:
Groundwater flow in an aquifer has frequently been found to be non-Darcian by performing in situ tests. A novel analytic model is proposed in this study for describing the unsteady non-Darcian flow in a confined aquifer by taking advantage of the observed flow rate and injection pressure during the constant head packer test. A linearization approximation of the Izbash equation is used to approximate the nonlinear term in the governing equation. This analytic model is applied to describe the non-Darcian flow in the interlayer staggered zone at the Baihetan hydropower station, China. The test results inversed by the genetic algorithm show that non-Darcian flow happened during the test under the injection pressure 0.3 MPa with the power index n is 1.278, non-Darcian hydraulic conductivity k 1 is 1.613 × 10 − 5 cm/s and the specific storage S s is 9.757 × 10 − 5 m-1, respectively. The sensitivity analysis indicated that when the power index n or the specific storage S s is larger, and the hydraulic head will increase more slowly and needs longer to stabilize, but the non-Darcian hydraulic conductivity k 1 shows the opposite trend. Moreover, the hydraulic head is more sensitive to the power index n compared to other parameters at late times. The findings of this study reveal the non-Darcian flow during the constant head packer test and provide a simple and fast way to estimate parameters for more accurate seepage field simulation.
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Jia, Wen Hua, Chen Bo Yin, and Dong Hui Cao. "Research of Median-Nonlinear Flow of Proportional Valve." Applied Mechanics and Materials 488-489 (January 2014): 1231–34. http://dx.doi.org/10.4028/www.scientific.net/amm.488-489.1231.
Повний текст джерелаАнотація:
In the traditional proportional valve mathematical model, the nonlinear flow characteristics induced by the geometrical features in various flow areas were often ignored. To overcome this problem, the uniform nonlinear flow mathematical model for the electro-hydraulic proportional valve is constructed. The relational expression between the orifice flow of the proportional valve and the geometrical future and physical characteristics of spool is constructed to obtain a series continuous nonlinear flow equations of median positive overlap, negative overlap and zero overlap proportional valve. The experiment validates that, for positive overlap, the flow input into the hydraulic tank is proportional to the displacement of the spool in the dead zone. For negative overlap, even though the spool located at the median, the flow output also exists, and induces the piston movement of hydraulic tank. This situation is consistent with the non-matching overlap response of actual negative proportional valve.
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Dedulina, E. A., P. Yu Vasilevskiy, and S. P. Pozdniakov. "Sensitivity of recharge estimation to the pore connectivity parameter of vadose zone rocks." Moscow University Bulletin. Series 4. Geology, no. 1 (February 28, 2020): 81–87. http://dx.doi.org/10.33623/0579-9406-2020-1-81-87.
Повний текст джерелаАнотація:
Information on recharge value is necessary for solving different classes of hydrogeological problems. One of the methods of recharge estimation is simulation of flow in vadose zone. Soil hydraulic parameters are used to estimate recharge by flow in vadose zone. One of the hydraulic parameters is the pore connectivity parameter l. The sensitivity of estimated recharge to the value of pore connectivity parameter, especially under humid climate conditions, is studied insufficiently. In present study, the experimental values of soil hydraulic parameters of samples from two different sites with various landscape conditions and vadose zone structure (forest landscape on sand and field landscape on loam) were used to estimate recharge.Recharge estimation was also carried for the value of l=0,5 and for reported values of l parameter for certain type of sediment. Analysis of calculation results demonstrated that using fixed value of l=0,5 leads to significant overestimation of calculated recharge both for forest and filed landscapes, which emphasizes the importance of experimental definitions of soil hydraulic parameters for recharge estimation. The analysis of the water balance components showed that the increase of estimated recharge with enhancement of l value is mainly associatedwith the decrease of evaporation from the upper soil layer.
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Wolski, Krzysztof, Tomasz Tymiński, and Grzegorz Chrobak. "Numerical modeling of the hydraulic impact of riparian vegetation." E3S Web of Conferences 44 (2018): 00194. http://dx.doi.org/10.1051/e3sconf/20184400194.
Повний текст джерелаАнотація:
This paper presents results of numerical modelling of riverbed segment with riparian vegetation performed with use of CCHE2 software. Vegetation zones are places where dynamic of water flow increases. Therefore, there is a need of careful examination of hydraulic impact structure of such zones. Accurate research is necessary and should be performed with use of physical or numerical models, two or three dimensional. Paper presents distribution of velocity and area of water surface for two variants of vegetation deposition acquired in CCHE2D software and modelled for riverbed with distinctive riparian vegetation. Results point to significant (30–40%) increase of maximal velocities in riverbed with riparian vegetation, while directly near the vegetation there were zones with very low velocities. Local damming occurs before vegetal zone. Maximal shear stress in zones with increased velocity is significantly augmented compared to conditions with no vegetation, which can cause more intensive erosion in those zones
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Arkhipov, B. V., V. N. Koterov, A. S. Kochetova, V. V. Solbakov, and G. M. Khublaryan. "Modeling of Flow at Hydraulic Structures in the Shelf Zone of Seas." Water Resources 30, no. 6 (November 2003): 653–58. http://dx.doi.org/10.1023/b:ware.0000007592.61838.1d.
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SAYRIDDINOV, S. Sh. "NONSTATIONARY WATER FLOW PARAMETERS ANALYSIS IN THE FLOWING ZONE THAT IS PAST WEIR." Urban construction and architecture 3, no. 4 (December 15, 2013): 44–48. http://dx.doi.org/10.17673/vestnik.2013.04.8.
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Supercritical water flow passing through the broadcrested weir has been experimentally examined. Engineering-based results on hydraulic-jump wave length and conjugated depths measurement considering the weir geometrical characteristics changers.
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Butakova, E. R., А. А. Sekacheva, and А. S. Noskov. "Study of operation of spool hydraulic control unit that transmits reduced pressure signal to control hydraulic distributors, control cylinders, parameters of axial piston pumps and hydraulic motors." Omsk Scientific Bulletin. Series Aviation-Rocket and Power Engineering 6, no. 1 (2022): 64–74. http://dx.doi.org/10.25206/2588-0373-2022-6-1-64-74.
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The article discusses the test results of three modernized hydraulic control units. In the course of the experiments, the nodes are refined with subsequent refinement tests. As a result, of the research, the following results are obtained: a characteristic of the dependence of the differential pressure on the flow rate, a dependence of the reduction pressure on the angle of the handle, pressure drops in the working bends of the control unit, etc. The analysis of the results and comparison with theoretical calculation shows that there are three main types of adjustment characteristics: parallel theoretical —with laminar flow, three — zone and quadratic — with turbulent mode.
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Yan, Xiaotong, Kan Kan, Yuan Zheng, Huixiang Chen, and Maxime Binama. "Entropy Production Evaluation within a Prototype Pump-Turbine Operated in Pump Mode for a Wide Range of Flow Conditions." Processes 10, no. 10 (October 12, 2022): 2058. http://dx.doi.org/10.3390/pr10102058.
Повний текст джерелаАнотація:
Inside the pump-turbine, energy is irreversibly lost due to turbulent pulsations in the high Reynolds number zone and actions of viscous forces close to the wall. The conventional differential pressure method cannot obtain specific details of the hydraulic loss within the machine’s flow passages; on the other hand, the entropy production method can provide accurate information on the location of irreversible losses and the spatial distribution of energy dissipation. Therefore, based on the entropy production theory, this study investigates the composition and distribution of hydraulic losses under different flow conditions for a prototype pump-turbine in pump mode. Study results indicated that total hydraulic losses significantly decreased, then slowly increased with an increase in flow rate. The entropy production rate caused by turbulence dissipation (EPTD), direct dissipation (EPDD), and wall shear stress (EPWS) displayed the same variation patterns as that of total hydraulic losses, with EPTD and EPDD being the most dominating. The location of hydraulic loss within the pump-turbine’s flow domain strongly depended on flow conditions. High hydraulic losses primarily occurred in the guide vanes (GV) and draft tube under low flow rates. Under high flow conditions, however, high hydraulic losses were mostly concentrated in the stay vanes (SV), spiral casing, and GV. Hydraulic losses at low flow rates were primarily caused by flow separation within the GV flow channels, vortices in the vaneless region, and inlet flow impacts on the runner blade’s leading edge. On the other hand, large vortices within the GV and SV flow channels, GV wake flow, and unsteady flow at the spiral casing were the main contributors to hydraulic loss under high flow conditions. EPDD was mainly caused by strain rate, so it was closer to the main vortex regions, whereas EPTD was affected by turbulence intensity and had a wider distribution range in the unsteady flow.
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Sannino, Gianmaria, Lawrence Pratt, and Adriana Carillo. "Hydraulic Criticality of the Exchange Flow through the Strait of Gibraltar." Journal of Physical Oceanography 39, no. 11 (November 1, 2009): 2779–99. http://dx.doi.org/10.1175/2009jpo4075.1.
Повний текст джерелаАнотація:
Abstract The hydraulic state of the exchange circulation through the Strait of Gibraltar is defined using a recently developed critical condition that accounts for cross-channel variations in layer thickness and velocity, applied to the output of a high-resolution three-dimensional numerical model simulating the tidal exchange. The numerical model uses a coastal-following curvilinear orthogonal grid, which includes, in addition to the Strait of Gibraltar, the Gulf of Cadiz and the Alboran Sea. The model is forced at the open boundaries through the specification of the surface tidal elevation that is characterized by the two principal semidiurnal and two diurnal harmonics: M2, S2, O1, and K1. The simulation covers an entire tropical month. The hydraulic analysis is carried out approximating the continuous vertical stratification first as a two-layer system and then as a three-layer system. In the latter, the transition zone, generated by entrainment and mixing between the Atlantic and Mediterranean flows, is considered as an active layer in the hydraulic model. As result of these vertical approximations, two different hydraulic states have been found; however, the simulated behavior of the flow only supports the hydraulic state predicted by the three-layer case. Thus, analyzing the results obtained by means of the three-layer hydraulic model, the authors have found that the flow in the strait reaches maximal exchange about 76% of the tropical monthlong period.
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Scalia, Joseph, and Craig H. Benson. "Preferential flow in geosynthetic clay liners exhumed from final covers with composite barriers." Canadian Geotechnical Journal 47, no. 10 (October 2010): 1101–11. http://dx.doi.org/10.1139/t10-018.
Повний текст джерелаАнотація:
Geosynthetic clay liners (GCLs) were exhumed from final covers with composite barriers (geomembrane over GCL) at two municipal solid waste landfills in the USA. Preferential flow and high hydraulic conductivity (>2 × 10−9 m/s) was observed in eight of the 18 GCL samples collected from both sites. At one site, manganese oxide precipitate was concomitant with bundles of needle-punched fibers that conducted preferential flow. Nearly complete replacement of Na by Ca on the bentonite surface occurred in all GCL samples. GCLs with and without preferential flow could not be differentiated by physical and chemical properties commonly used to differentiate GCLs with high and low hydraulic conductivities (exhumed water content, swell index, mole fraction monovalent cations, soluble cation concentrations). The relative abundance of soluble cations in the pore water of GCLs exhibiting preferential flow was comparable to the relative abundance in the subgrade pore water, whereas the pore water in GCLs with distributed flow was more sodic than the pore water in the subgrade. Hydration experiments indicated that bentonite in GCLs initially hydrates in a zone surrounding bundles of needle-punching fibers. Cation exchange during this hydration process may create zones of higher hydraulic conductivity surrounding the fiber bundle, permitting preferential flow.
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Bing, Hao, and Shuliang Cao. "Parametrization of blade leading and trailing edge positions and its influence on mixed-flow pump performance." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 4 (May 15, 2013): 703–14. http://dx.doi.org/10.1177/0954406213490104.
Повний текст джерелаАнотація:
Based on the three-dimensional design platform, this article conducted parametrization of blade leading and trailing edge positions, and analyzed the influence of different position parameters on mixed-flow pump hydraulic performance and internal flow with model test and numerical simulation. The results showed that the hydraulic efficiency η of a mixed-flow pump increased slightly when the position parameter θh of the blade leading edge on the hub increased, and η increased significantly when the position parameter θt of the blade leading and trailing edge positions on the shroud increased. However, with θt increasing, the growth rate of η decreased. Numerical simulation has shown that by selecting a proper value of θt, the impeller energy conversion capacity can be effectively improved, and the distributions of static pressure and total energy can be more uniform in the flow passage. Meanwhile, with θt increasing, blade angle on the blade trailing edge decreased. Correspondingly, the absolute velocity in the outlet zone decreased, and the hydraulic loss in the outlet zone also decreased, which is beneficial to improving hydraulic efficiency of the mixed-flow pump. Within the value range of 7–9°, with different combinations of position parameter θt1 of the blade leading edge on the shroud and position parameter θt2 of the blade trailing edge on the shroud, the mixed-flow pump hydraulic efficiency η and blade wrap angle ϕ show a linear positive correlation, suggesting that an increase in ϕ could significantly improve impeller energy conversion capacity. Compared to θt1, θt2 has a more significant influence on ϕ and η. Thus, the value of θt2 should be carefully attended to during design process.
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Donzé, Frédéric-Victor, Alexandra Tsopela, Yves Guglielmi, Pierre Henry, and Claude Gout. "Pressurized fluid flow within the mechanical stability domain of fault zones in shale." E3S Web of Conferences 98 (2019): 01013. http://dx.doi.org/10.1051/e3sconf/20199801013.
Повний текст джерелаАнотація:
Fracture interaction mechanisms and reactivation of natural discontinuities under fluid pressurization conditions inside fault zone can represent critical issues in risk assessment of caprock integrity. A field injection test, carried out in a damage fault zone at the decameter scale i.e. mesoscale, has been studied using a Distinct Element Model. Considering the complex structural nature of a fault zone, the contribution of fracture sets on the bulk permeability has been investigated during a hydraulic injection. It has been shown that their orientation for a given in-situ stress field plays a major role. However, if homogeneous properties are assigned to the fracture planes in the model, the limited irreversible displacements cannot be reproduced. Despite these limited displacements (40 µm maximum), the transmissivity increased by a factor of 10-100. These results provide insights in fracture controlled permeability of fault zones depending on the geometrical properties of the fractures and their resulting hydro-mechanical behavior for a given in–situ stress field.
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Earon, Robert, Joakim Riml, Liwen Wu, and Bo Olofsson. "Insight into the influence of local streambed heterogeneity on hyporheic-zone flow characteristics." Hydrogeology Journal 28, no. 8 (October 2, 2020): 2697–712. http://dx.doi.org/10.1007/s10040-020-02244-5.
Повний текст джерелаАнотація:
AbstractInteraction between surface water and groundwater plays a fundamental role in influencing aquatic chemistry, where hyporheic exchange processes, distribution of flow paths and residence times within the hyporheic zone will influence the transport of mass and energy in the surface-water/groundwater system. Geomorphological conditions greatly influence hyporheic exchange, and heterogeneities such as rocks and clay lenses will be a key factor for delineating the hyporheic zone. Electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) were used to investigate the streambed along a 6.3-m-long reach in order to characterise geological layering and distinct features which may influence parameters such as hydraulic conductivity. Time-lapse ERT measurements taken during a tracer injection demonstrated that geological features at the meter-scale played a determining role for the hyporheic flow field. The penetration depth of the tracer into the streambed sediment displayed a variable spatial pattern in areas where the presence of highly resistive anomalies was detected. In areas with more homogeneous sediments, the penetration depth was much more uniformly distributed than observed in more heterogeneous sections, demonstrating that ERT can play a vital role in identifying critical hydraulic features that may influence hyporheic exchange processes. Reciprocal ERT measurements linked variability and thus uncertainty in the modelled resistivity to the spatial locations, which also demonstrated larger variability in the tracer penetration depth, likely due to local heterogeneity in the hydraulic conductivity field.
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Huang, C. S., S. Y. Yang, and H. D. Yeh. "Technical Note: Approximate solution of transient drawdown for constant-flux pumping at a partially penetrating well in a radial two-zone confined aquifer." Hydrology and Earth System Sciences 19, no. 6 (June 5, 2015): 2639–47. http://dx.doi.org/10.5194/hess-19-2639-2015.
Повний текст джерелаАнотація:
Abstract. An aquifer consisting of a skin zone and a formation zone is considered as a two-zone aquifer. Existing solutions for the problem of constant-flux pumping in a two-zone confined aquifer involve laborious calculation. This study develops a new approximate solution for the problem based on a mathematical model describing steady-state radial and vertical flows in a two-zone aquifer. Hydraulic parameters in these two zones can be different but are assumed homogeneous in each zone. A partially penetrating well may be treated as the Neumann condition with a known flux along the screened part and zero flux along the unscreened part. The aquifer domain is finite with an outer circle boundary treated as the Dirichlet condition. The steady-state drawdown solution of the model is derived by the finite Fourier cosine transform. Then, an approximate transient solution is developed by replacing the radius of the aquifer domain in the steady-state solution with an analytical expression for a dimensionless time-dependent radius of influence. The approximate solution is capable of predicting good temporal drawdown distributions over the whole pumping period except at the early stage. A quantitative criterion for the validity of neglecting the vertical flow due to a partially penetrating well is also provided. Conventional models considering radial flow without the vertical component for the constant-flux pumping have good accuracy if satisfying the criterion.
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Shanmugam, Mohanasundaram, G. Suresh Kumar, Balaji Narasimhan, and Sangam Shrestha. "Effective saturation-based weighting for interblock hydraulic conductivity in unsaturated zone soil water flow modelling using one-dimensional vertical finite-difference model." Journal of Hydroinformatics 22, no. 2 (December 9, 2019): 423–39. http://dx.doi.org/10.2166/hydro.2019.239.
Повний текст джерелаАнотація:
Abstract Richards equation is solved for soil water flow modeling in the unsaturated zone continuum. Interblock hydraulic conductivities, while solving for Richards equation, are estimated by some sort of averaging process based on upstream and downstream nodes hydraulic conductivity values. The accuracy of the interblock hydraulic conductivity estimation methods mainly depends on the distance between two adjacent discretized nodes. In general, the accuracy of the numerical solution of the Richards equation decreases as nodal grid discretization increases. Conventional interblock hydraulic conductivity estimation methods are mostly mere approximation approaches while the Darcian-based interblock hydraulic conductivities involve complex calculations and require intensive computation under different flow regimes. Therefore, in this study, we proposed an effective saturation-based weighting approach in the soil hydraulic curve functions for estimating interblock hydraulic conductivity using a one-dimensional vertical finite-difference model which provides a parametric basis for interblock hydraulic conductivity estimation while reducing complexity in the calculation and computational processes. Furthermore, we compared four test case simulation results from different interblock hydraulic conductivity methods with the reference solutions. The comparison results show that the proposed method performance in terms of percentage reduction in root mean square and mean absolute error over other methods compared in this study were 59.5 and 60%, respectively.
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Carpenter, Kenneth. "Hydraulic modeling and computational fluid dynamics of bone burial in a sandy river channel." Geology of the Intermountain West 7 (April 30, 2020): 97–120. http://dx.doi.org/10.31711/giw.v7.pp97-120.
Повний текст джерелаАнотація:
An oval recycling flume with live-beds (moveable) of medium and very coarse grained sands were used to explore the process of bone burial as a precursor to fossilization. Two-dimentional computation fluid dynamics was used to visualize and interpret the flow turbulence around bones. Results show that a water mass approaching and passing a static bone (obstruction) is subjected to flow modification by flow separation, flow constriction, and flow acceleration producing complex flow patterns (turbulence). These complex patterns include an upstream high-pressure zone, down flows, and vortices (with flow reversal near the bed) causing bed shear stress that produce bed erosion. Downstream of the bone, the water mass undergoes flow deceleration, water recirculation (turbulence eddies), flow reattachment, low-pressure zone (drag), and sediment deposition. Scour plays a crucial role by undercutting bone on the upstream side and may cause the bone to settle into the bed by rotation or sliding. Scour geometry is determined by bone size and shape, approaching flow velocity and angle to flow, flow depth, bed topography, and bed friction. Drag on the downstream side of the bone causes scoured sediment deposition, but burial by migrating bed forms is the most important method of large bone burial. Bone may be repeatedly buried and exposed with renewed scour. However, each episode of scour may lower the bone deeper into the bed so that it essentially buries itself. No difference in these effects were noted between experiments using fine or coarse grain sizes. This experimental work is then used to interpret the possible history of bone burial in the Upper Jurassic Morrison Formation on the bone wall inside the Quarry Exhibit Hall at Dinosaur National Monument, Utah.