Water Flow Area Research Articles

Experimental and CFD investigation of cavitation phenomenon in the distributor of a Banki-Michell Turbine

Cavitation is a physical phenomenon that often occurs in hydraulic machines such as pumps, valves, and turbines. Although the Banki-Michell turbine has been used for a long time in small hydropower, no study related to this phenomenon of cavitation in the injector of this turbine has been done. In this study, we will present the results of a numerical study carried out in the nozzle of a Banki-Michell turbine. The numerical solution of the Navier Stokes cavitation equations of the Banki-Michell turbine injector was carried out considering a 2D geometry of the injector-rotor assembly. The simulation results showed that the cavitation phenomenon appears when the water flow area in the nozzle becomes less than 50%. Furthermore, the results also showed that the occurrence of this cavitation phenomenon in the injector is more likely at higher operating heads. The results of an experimental study of the geometry of the injector showed that the height of the water passage section varies linearly with the degree of opening of the stator valve.

Passive Microwave Radiometry at Different Frequency Bands for River Discharge Retrievals

AbstractThe present era of climate change and expanding population requires major improvements in sustained observation of global river discharge. Floods and droughts are affecting food supplies, and suspected long‐term trends require appropriate data for evaluation. Orbital remote sensing can address this observational need. Here we use satellite Ka‐ (36.5 GHz) and L‐band (1–2 GHz) passive microwave radiometry (PMR) to monitor river discharge changes and determine what size rivers can be measured and the frequencies and polarization configurations that yield the most robust results. Selected satellite gauging reaches (SGRs) can be measured at near‐daily intervals from 1998 to present (Ka‐band) and 2010 to present (L‐band). The SGRs are 10–36 km in length; the dynamic proportion of water surface area within each varies with river discharge. Due to contrasting dielectric properties, water and land emit different intensities of microwave radiation; thus emission from a mixed water/land pixel decreases as the proportion of water within the pixel increases. Depending on the river and floodplain morphology, water flow area can be a robust indicator of discharge and the microwave sensors can retrieve daily discharge to ±20%. Instead of spatial resolution, it is the sensor measurement precision, geolocation accuracy, and channel and floodplain morphology that most strongly affect accuracy. Calibration of flow area signals to discharge can be performed using nearby ground stations (even if now discontinued) or by comparison to hydrologic modeling.

Genetic diversity and structure of Brycon henni in regulated and non-regulated water flow rivers of the Colombian Andes

The sabaleta, Brycon henni, is a medium-size fish species found in the Andean range of the Magdalena-Cauca river basin in Colombia, where it is a fishery resource. Recruitment of sabaleta has affected construction of dams with unknown consequences on its genetic diversity and structure. Understanding the current genetic architecture in the dam-influenced areas compared to non-regulated water flow systems is crucial to diagnose the impact of human interventions and formulate proper management strategies. In this study, we evaluated the genetic structure and diversity of B. henni by using a set of microsatellites in individuals from 14 localities to identify the number of distinct genetic pools. We used various approaches to compare populations between regulated and non-regulated areas in the Magdalena-Cauca basin, and identified eleven well-differentiated and highly diverse population groups with marked genetic structures at local and regional levels. Genetic diversity of B. henni was very similar among non-regulated and dam-regulated water flow areas; however, one of the populations in non-regulated areas showed evidence of a founder effect associated with recent introductions. The effect of dams on the genetic structure of B. henni in the Magdalena-Cauca basin was negligible, probably due to their recent construction. Future reduction of genetic diversity and the loss of unique populations is expected due to the combined effect of geographic isolation and population declines. Thus, monitoring programs are necessary to detect changes in the genetic structure of fish populations to develop useful conservation actions.

Recommendations for planning water infrastructure in the Surabaya City area with the influence of watershed characteristics to realize sustainable settlement drainage that is safe from flooding

The development of urban areas often has an impact on changes in the surface run off area of water flow, a consequence that often occurs is flooding due to an increase in the value of run off drainage from housing/industries which burdens the capacity of urban land drainage channels. The analysis carried out is to calculate the value of the travel time (Tc) from the build area compared to the peak time (Tp) in the urban partial drainage flow. The value of time concentration is influenced by the slope of topography and watershed area of each rayon in Surabaya. The calculated Tc and Tp values will be combined to find the linear correlation value of the effect of watershed characteristics on development/change of land area in Surabaya. The results of the linear analysis of the relationship between the area of the build up area and the combined travel time in each rayon are not the same, this is due to the influence of land topographic slopes in each rayon and also the area of the watershed be different. the length of the channel on the drainage of urban area in each rayon have a separate drainage network sub system from one another. This is a consideration that the determination of the formulation of the relationship between the area of the build up area and the time and volume of the reservoir must adjust the characteristics of each rayon.

Mine safety and risk prediction mechanism through nanocomposite and heuristic optimization algorithm

Worker's safety and water quality maintenance are the two predominant process that is followed inside the Mines. Many models had been proposed in the past to enhance the whole process but they failed to do so due to the practical limitations in the deployment in terms of cost. Though technology had improved much, human intervention is still unavoidable in mines. Considering the practical issues, in this article, a novel methodology using the Internet of Things (IoT) is proposed. This study is mainly focused on the change in the geometry/structure of the coal mining field due to pressure and water contamination that occurs in the region during coal extraction. Several sensors are adopted to measure the water quality and computational technique is used to analyze roof pressure variation in the coalfield. The roof pressure experienced by the nascent structure is compared with a structure that is roof bonded with a glass fiber composite layer. The significance of nanofiber technology is analyzed and reported. To ensure water quality, Harmonic Water Optimization (HWO) Algorithm is developed, here 10 different water flow areas are chosen and their corresponding data is gathered using IoT sensors. Harmony Management Preprocessing (HMP) Algorithm is developed to preprocess the redundant and ambiguous data. Heuristic Fusion Clustering (HFC)algorithm is developed for the data fusion, which can cluster and improve the data quality. The analysis of the proposed work reveals that it would greatly improve the sustainable development of mining safety and water quality which is the most vital factor.

Recreation and Tourism Service Systems Featuring High Riverbanks in Taiwan

Taiwan’s cities exhibit high levels of urbanization, which has resulted in limited recreation space in urban areas. In response, government policies have been enacted to promote the large-scale greening of rivers in urban areas and the establishment of aquatic recreation areas that do not interfere with water flow areas, pavilions for recreation purposes, indoor stadiums, and biking lanes alongside riverbanks to provide citizens with recreation space. An expert team was convened to investigate 50 riverside recreation sites, and the Comfortable Water Environment Rest Assessment Form was devised. The investigation results revealed three factors that contribute to the value of riverside recreation sites; the three factors had a total explanatory power of 70.17%. The factors, namely exercising and leisure, overall design plan and entrance image, and environmental maintenance and service, had an explanatory power of 25.52%, 23.32%, and 21.32%, respectively. Finally, this study provides guidance for constructing service systems for riverside recreation sites by referencing practical cases. This study suggests that future designs focus on the characteristics of visitors as the main consideration when investing resources in recreation sites. In addition, more exercise and recreation equipment and facilities should be provided at recreation sites located within highly populated areas. For recreation sites that feature beautiful scenery, greater degrees of overall design planning and entrance image qualities can be integrated into the recreation sites, and environmental teaching materials can be incorporated into the environment. Furthermore, this study suggests that residents who live near recreation sites form and operate volunteer groups to contribute to environmental maintenance and the relevant services; this would greatly enhance the overall experience of comfort of visitors to the recreation sites. Finally, this study provides guidance for low-intensity construction in high riverbank areas.

Study of the technogenesis of the Degtyarsky mine by audio-magnetotelluric express sounding

The audio-magnetotelluric express sounding was performed at four sections crossing the mine field of the currently not functioning Degtyarsky mine. Field measurements were carried out by a universal broadband receiver “OMAR-2m” with active electromagnetic field sensors developed at the Institute of Geophysics UB RAS. Based on the obtained data, deep sections of the electrophysical parameters of the medium – apparent resistivity and effective longitudinal conductivity – are drawn. The nature of the geoelectric structure of the section allows mapping of the major lithochemical contamination plume and identifying the tectonic disturbance zones that drain aggressive mine waters. The mine waters of the Degtyarsky mine are a source of dangerous technogenic pollution. Despite the neutralization of surface runoff, underground routes of acidic water migration occur along tectonic cracks, primarily in the zone of the regional Serovsko-Mauksky fault. Tectonic zones in the mine area contain contaminated fissure-vein water, which is transited at a depth of 70 to over 200 m. Discharging ascending springs of such waters can be located at a great distance from controlled hydrological objects and pollute sources of drinking and household water supply. Urban development in the western and eastern parts of Degtyarsk does not fall within the distribution zone of polluted water. The southern part of the city is located beyond the watershed of the mine water flow area, but a danger of local contamination by tectonic disturbance zones remains possible. The worst environmental situation is observed in the northern outskirts of Degtyarsk, which falls into the area of heavy pollution of underground and surface waters. Besides, acidic fumes from the flooded Kolchedanny quarry can affect the health of city residents when emitted to the atmosphere.

Experimental and numerical study on implosion protection of large format photo-multiplier tubes

As the hollow structures are prone to implosion in deepwater environments, which will result in catastrophic accidents, the implosion protection of photo-multiplier-tubes (PMTs) is an important issue in the design and operation of large format underwater neutrino detectors. In this paper, the implosion protection of dense layout large format PMT was investigated, and the implosion protective device was designed. Specifically, the steel-made compressive sealed container was used to simulate the deepwater environment, and the PMT implosion experiment was carried out at a water depth of 40 m. The underwater implosion process and flow field pressure were recorded. The experimental results showed that the protective device could significantly reduce the shock wave intensity generated by the implosion and diminish the occurrence of large-scale sympathetic implosion. In order to reveal the protection design mechanism, the PMT implosion simulation was carried out. The calculation results showed that the peak pressure of the shock wave generated by the implosion decreased as the hydrostatic pressure, the area and the impact angle of the water flow reduced respectively. Then, the empirical formula of hydrostatic pressure and the area of water flow with the peak of the shock wave pressure were obtained. This study laid a solid foundation of guidance for the engineering implosion protection design of large format PMT and other deepwater hollow structures.

Flow characteristics of water delivery piping system and its effective flow area at discharge branches

When we scatter water uniformly over a wide area, we often make a large number of branches and discharge outlets in a main pipe and let water be discharged from each outlet. In order to achieve uniform sprinkling, it is necessary to understand the state of the water flowing out from each outlet properly. In the present paper, the flow field inside a water delivery pipe with multiple short branch pipes was investigated using numerical calculation and experimental measurement. As a result, computational results and experimental results showed good agreement, and the validity of the computational method was confirmed. At the discharge outlet, flow surface in which air and water were mixed was formed. It was confirmed that the water area was smaller on the upstream side and became larger as going downstream. It was clarified that the discharge flow rate and the water flow area changed greatly due to the change in the discharge outlet diameter and the terminal outlet diameter.

3D modelling of the climatic impact of outflow channel formation events on early Mars

Mars was characterized by cataclysmic groundwater-sourced surface flooding that formed large outflow channels and that may have altered the climate for extensive periods during the Hesperian era. In particular, it has been speculated that such events could have induced significant rainfall and caused the formation of late-stage valley networks. We present the results of 3-D Global Climate Model simulations reproducing the short and long term climatic impact of a wide range of outflow channel formation events under cold ancient Mars conditions. We find that the most intense of these events (volumes of water up to 107 km3 and released at temperatures up to 320 K) cannot trigger long-term greenhouse global warming, regardless of how favorable are the external conditions (e.g. obliquity and seasons). Furthermore, the intensity of the response of the events is significantly affected by the atmospheric pressure, a parameter not well constrained for the Hesperian era. Thin atmospheres (P < 80 mbar) can be heated efficiently because of their low volumetric heat capacity, triggering the formation of a convective plume that is very efficient in transporting water vapor and ice at the global scale. Thick atmospheres (P > 0.5 bar) have difficulty in producing precipitation far from the water flow area, and are more efficient in generating snowmelt. In any case, outflow channel formation events at any atmospheric pressure are unable to produce rainfall or significant snowmelt at latitudes below 40°N. As an example, for an outflow channel event (under a 0.2 bar atmospheric pressure and 45° obliquity) releasing 106 km3 of water heated at 300 K and at a discharge rate of 109 m3 s−1, the flow of water reaches the lowest point of the northern lowlands (around ∼70°N, 30°W) after ∼3 days and forms a 200 m deep lake of 4.2 × 106 km2 after ∼20 days; the lake becomes entirely covered by an ice layer after ∼500 days. Over the short term, such an event leaves 6.5 × 103 km3 of ice deposits by precipitation (0.65% of the initial outflow volume) and can be responsible for the melting of ∼80 km3 (0.008% of the initial outflow volume; 1% of the deposited precipitation). Furthermore, these quantities decrease drastically (faster than linearly) for lower volumes of released water. Over the long term, we find that the presence of the ice-covered lake has a climatic impact similar to a simple body of water ice located in the Northern Plains.For an obliquity of ∼45° and atmospheric pressures > 80 mbar, we find that the lake ice is transported progressively southward through the mechanisms of sublimation and adiabatic cooling. At the same time, and as long as the initial water reservoir is not entirely sublimated (a lifetime of 105 martian years for the outflow channel event described above), ice deposits remain in the West Echus Chasma Plateau region where hints of hydrological activity contemporaneous with outflow channel formation events have been observed. However, because the high albedo of ice drives Mars to even colder temperatures, snowmelt produced by seasonal solar forcing is difficult to attain.

Experimental investigations on Darrieus straight blade turbine for tidal current application and parametric optimization for hydro farm arrangement

The energy flow rate per unit flow area of water flow is quite high compared to air flow. This is because of high density of water compared to that of air. Hence, hydrokinetic turbine has the potential to extract more power compared to wind turbine for the same size of a turbine. The Darrieus turbine is one of the best options which can be used as a hydrokinetic turbine due to its high coefficient of power. In present work, the experimental investigations are carried out to study the hydrodynamic performance of three bladed Darrieus turbine with NACA0015, NACA0018 and NACA4415 blades for different solidities. Maxwell’s velocity correction method is used to account for blockage effect. NACA0015 and NACA0018 provide highest coefficient of power of 0.15 at a solidity of around 0.382. Experiments are extended to evaluate performance for four bladed rotors with symmetric-NACA0018 and cambered-NACA4415 hydrofoils. Both the hydrofoils provide a coefficient of power of around 0.13 but at different solidities. The effect of spanwise and streamwise distance on performance of a Darrieus turbine is investigated for its use as hydrofarm. A minimum distance of 7D along the streamwise direction and 3D along the spanwise direction are essential in a hydrofarm using Darrieus turbines.

Warunki geologiczno-inżynierskie na obszarze strefy krawędziowej Wzgórz Warszewskich

&lt;p&gt;Development trends of the modern city imply a reduction in the number of inhabitants in its centre, and thus the construction of dormitory suburbs on the outskirts of the city. One of the potential areas for the development ofSzczecinis its northern part, i.e. the so-called Warszewo Hills. This area has both latitudinal and meridional extents of about 8 km, and is characterized by complicated engineering-geological conditions. It lies at altitudes ranging from the sea level (OdraRiver) to 130.9 m a.s.l. (Wielecka Góra), and has very varied relief. Its landscape consists of hills and flat plateaux, which are cut by deep small valleys, some of them with streams (e.g. the Warszewiec stream). Geological structure is characterized by the occurrence of glacitectonically disturbed moraine deposits mixed with the Tertiary sands and clays. Taking into account geodynamic processes and their intensity, the wide edge zone of the Warszewo Hills can be divided into three main parts: plateau with the upper edge of slope (area of precipitation infiltration), slope, which is cut by small erosion valleys in places (area of surface water and groundwater flow), slope foot (area of water flow and accumulation of slope deposits). One of the most important tasks of the design-investment process is to take action in such a way as to interfere as little as possible in the natural environment and at the same time to achieve the intended purpose. Predominant occurrence of cohesive deposits in the described area (Oligocene scaled clay mixed with moraine disturbed material) results in a high susceptibility of ground to moisture changes. Strength parameters of stable slopes built of clays considerably decrease under the influence of increasing moisture and thixotropy phenomenon. Then landslide processes are triggered, as well as very slow, hardly noticeable in a short time, soil creep. The complicated arrangement of deposit layers results in spatial variability of groundwater level, and proper design of building foundation is difficult, even in the case of a small, detached house. Too much interference in the landform features (through macro-levelling, construction of streets and routes in the area with steep slopes), the decrease of water retention and increase of surface runoff contribute to an intensification of some geodynamic processes. &lt;/p&gt;

Lead (Pb) Accumulation in Water, Sediment and Mussels (Hiatula chinensis) from Pasir Panjang Coast, Lekok-Pasuruan

This study attempted to evaluate Pb accumulation in the water, sediment and mussels ( Hiatula chinensis ) from Lekok-Pasuruan. There were four sampling stations representing the study area: (1) urban areas, (2) water flow area from steam power plant (PLTU), (3) waste disposal area of PLTU, (4) fishing port. The average concentration of lead varied between stations in the water (0.279 ppm), sediment (0.423 ppm) and mussels (0.427 ppm). Pearson`s correlation test shows strong relationship (p > 0.05) between Pb in the water, sediment and Hiatula chinensis . Mussels accumulation of lead from the sediment was assessed using bio-concentration factor (BCF) and the result shows Hiatula chinensis is an accumulator of Pb (BCF > 1).

Spatial and temporal trends for water-flow velocity and bed-material sediment transport in the lower Mississippi River

Where rivers near the coastline, the receiving basin begins to influence flow, and gradually varied, nonuniform flow conditions arise. The section of the river affected by nonuniform flow is typically referred to as the backwater segment, and for large lowland rivers, this portion of the river can extend many hundreds of kilometers above the outlet. River morphology and kinematics vary in the backwater segment; however, these channel properties have not been explicitly related to properties of the flow and sediment-transport fields. This study examines the influence of spatially and temporally varying flow velocity and sediment transport on channel properties for the lower 800 km of the Mississippi River, a section of the river that includes the backwater segment. Survey transects (n = 2650) were used to constrain the cross-sectional area of water flow every ∼312 m along the Mississippi River channel for eight successive intervals of water discharge. Assuming conservation of water discharge, the local flow velocity was calculated at each transect by dividing water discharge by the local measurement of cross-sectional flow area. Calculated flow velocity was converted to total bed stress using a dimensionless friction coefficient that was determined by optimizing the match between a predicted and a measured water-surface profile. Estimates for the skin-friction component of the total bed stress were produced from the values for total shear stress using a form-drag correction. These skin-friction bed-stress values were then used to model bed-material transport. Results demonstrate that in the lower Mississippi River, cross-sectional flow area increases downstream during low- and moderate-water discharge. This generates a decrease in calculated water-flow velocity and bed-material transport. During high-water discharge, the trend is reversed: Cross-sectional flow area decreases downstream, producing an increase in calculated water-flow velocity and bed-material transport. An important contribution of this work is the identification of a downstream reversal in the trend for channel cross-sectional area due to variable water discharge. By accounting for the spatial divergences in sediment transport predicted over an average annual hydrograph, we demonstrate the tendency for channel-bed aggradation in much of the backwater reach of the Mississippi River (150–600 km above the outlet); however, a region of channel-bed erosion is calculated for the final 150 km. These results help to explain the spatial variability of channel morphology and kinematics for the lower Mississippi River, and they can be extended to other lowland river systems near the coastline.

Differences in invertebrate infaunal assemblages of constructed and natural tidal flats in New South Wales, Australia

The infauna at four natural and two constructed tidal flats were sampled to determine differences in assemblages on the southeastern coast of New South Wales, Australia. Spatial variation within location (tidal heights and subsites separated by 50–100 m) and between locations was incorporated into the design to investigate differences in species assemblages between constructed and natural locations. Overall, infauna at constructed locations were intermediate in abundance and species richness, although differences in abundance and species richness across tidal heights were observed at some locations. Multivariate analysis of species composition revealed distinct differences in species assemblages between constructed and natural locations, amongst tidal heights, and considerable spatial variation within any location. Inappropriate design of waterflow at the oldest constructed site is believed to be responsible for the low variability in species assemblages within this location which are characterised by early successional species that occur in disturbed tidal flats. The newer constructed tidal flat appeared to have adequate waterflow, high site variability in species composition and an infaunal assemblage typical of an early successional stage. The importance of measuring spatial variability in monitoring is stressed in order to make useful comparisons between constructed and natural tidal flats. This study showed that the successful construction of a mature and healthy tidal flat requires the maintenance of a significant waterflow area to ensure adequate tidal flow for the establishment of fauna.

横浜・野島海岸における積算平均流速の簡易計測と二枚貝類の分布

To measure spatial distribution of water flow in tidal flat, a simple method using gypsum body was developed. Gypsum body dissolution rate in steady water flow was proportional to the velocity. The investigation about water flow with gypsum body and bivalves distribution was carried out in Nojima beach, Yokohama. Relationship was confirmed between velocity with flowmetry and calculated velocity with gypsum body. As a result, the method is applicable to measurement of cumulative-averaged velocity. The bivalves distribution in Nojima beach showed lower distribution at the north off shore, where is corresponded to high water flow area. It was implied that high water flow is one of restricted habitat factors of the bivalves in Nojima beach.

The Behavioral Response of Juvenile Red Snapper (Lutjanus campechanus) to Shrimp Trawls that Utilize Water Flow Modifications to Induce Escapement

Clear differences in swimming ability between finfish and shrimp in trawls have been utilized in the Southeastern U.S shrimp fishery to reduce the by catch of finfish. The Jones/Davis device which has been mandated for use in the Gulf of Mexico shrimp fishery uses four windows to provide an escape path for fish while a funnel keeps the shrimp away from the windows, reduces water flow around the windows, and acts as a leading panel to guide the fish out of the trawl. Observations of fish behavior showed that finfish generally reacted to the slack water flow created by the funnel by swimming towards the lowest water flow area. The escape rate of finfish such as juvenile red snapper (Lutjanus campechanus), however, was low and random during towing when no net surging and fish crowding occurred. The highest escape rates occurred during slow down prior to haulback, but were dependent on the haul back procedure. This may help explain the haul-to-haul variation in escapement documented for the Jones/Davis device. Modifications and techniques to improve escape rates during towing are discussed.

Study on Flow Resistance and Sediment Transport on the Bed with Sediment Deposition in Pipe

Resistance of pipe flow with a stationary bed and with bed load on sediment deposition in pipes is discussed theoretically and experimentally, in which water flow area and hydraulic radius in a cross section of the pipe is divided into two parts: area and hydraulic radius influenced by smooth pipe wall and those by rough sediment wall. Experimental results about mean velocity and sediment transport rate in a pipe proved that the division of hydraulic radius of the water flow area into two is useful for the estimation of flow resistance and bed shear stress

Size Determination of Partly Full Conduits

The transition from partly full to full pipe (sealing) is accompanied by vibrations of the structure and surging of the flow. The experimental study was done in a 4-in. (100-mm) square conduit with three different circular bends, with various deflectors, and with various concentrations of air. Sealing depends on the Froude number of the flow. To maintain partly full flow, more space is needed above the water-flow area with an increase of Froude number. With short-tube control, the ratio of the radius of curvature along the center line to the bend diameter and the deflector thickness at the crown of the bend determine the water-flow area in the horizontal conduit. Ventilation of the horizontal conduit delays sealing while aeration of the water flow hastens sealing. With weir control, waves on the flow surface hasten sealing and highly aerated flow delays sealing. Ratios of radius of curvature to the bend diameter larger than 2.0 are recommended, since they generate fewer waves.

HYDRAULIC PROPERTIES OF DISTURBED AND UNDISTURBED SOILS

Studies showed that sample disturbance influenced water retention, lower limit of available water and unsaturated hydraulic conductivity. Significant differences in water retention due to sample disturbance occurred more frequently at low than at high suction. Results showed that sample disturbance may influence unsaturated hydraulic conductivity by changing area of water flow and/or tortuosity. A modified Millington and Quirk method did not adequately predict measured hydraulic conductivity, in either disturbed or undisturbed soils. In view of theoretical objections to extension of capillary theory to the dry end of the available water range, and the relative ease of direct measurements, it is suggested that direct measurement is the only reliable procedure available.