Flow Height Research Articles

Meta-analysis of ecosystem services associated with oyster restoration.

Restoration of foundation species promises to reverse environmental degradation and return lost ecosystem services, but a lack of standardized evaluation across projects limits understanding of recovery, especially in marine systems. Oyster reefs are restored to reverse massive global declines and reclaim valuable ecosystem services, but the success of these projects has not been systematically and comprehensively quantified. We synthesized data on ecosystem services associated with oyster restoration from 245 pairs of restored and degraded reefs and 136 pairs of restored and reference reefs across 3500km of U.S. Gulf of Mexico and Atlantic coastlines. On average, restoration was associated with a 21-fold increase in oyster production (mean log response ratio=3.08 [95% confidence interval: 2.58-3.58]), 34-97% enhancement of habitat provisioning (mean community abundance=0.51 [0.41-0.61], mean richness=0.29 [0.19-0.39], and mean biomass=0.69 [0.39-0.99]), 54% more nitrogen removal (mean=0.43 [0.13-0.73]), and 89-95% greater sediment nutrients (mean=0.67 [0.27-1.07]) and organic matter (mean=0.64 [0.44-0.84]) relative to degraded habitats. Moreover, restored reefs matched reference reefs for these ecosystem services. Our results support the continued and expanded use of oyster restoration to enhance ecosystem services of degraded coastal systems and match many functions provided by reference reefs.

DETERMINACIÓN DEL CAUDAL VOLUMÉTRICO A LO LARGO DE UN ESTUARIO CON ONDA DE MAREA ESTACIONARIA

The hydrodynamic behaviour of the micro tidal and 13.9-km-long Quequén Grande River estuary (Buenos Aires, Argentina), in which the tide behaves as a standing wave, is studied analytically and numerically. Results provided by the SisBaHiA program are validated with the measurements performed with two acoustic Doppler current profilers in stations located at 1.4, 2.9, 7.5 and 11.3 km from the estuary mouth. The numerical model reproduces the differences between the measured water column height and the equilibrium height in each station. In particular, the numerical values of the flow and tidal height are analyzed during a spring tide cycle by considering nine times corresponding to the maximum, minimum, and close to the equilibrium levels. The time variations in the free surface height and flow along the estuary are explained successfully by an analytical model based on the Saint Venant one-dimensional equations as a function of the river discharge and the tidal height in the estuary mouth and the bed and friction slopes.

Experimental Analysis of Temperature-Control Curtain Regulating Outflow Temperature in a Thermal-Stratified Reservoir.

The construction of reservoir dams has changed the environment and natural properties of the river course, and deep-water reservoirs present an obvious phenomenon of thermal stratification. Low-temperature outflow water in spring and summer will have a negative impact on the downstream ecological environment. Therefore, it is necessary to take selective withdrawal measures to regulate low-temperature outflow water. The temperature-control curtain project has the advantages of low cost, convenient construction and wide application. Based on the topographic data, a laboratory test model for regulating outflow temperature by a temperature-control curtain is established. A high-power electric heating system is adopted to form a nonlinear thermal stratification. The accuracy of the test data is verified by the prototype observed water temperature. The main parameters affecting the outflow temperature are investigated, including thermal stratification, flow height above the temperature-control curtain, water level, and discharge flow. The results show the following: firstly, the outflow temperature mainly depends on the thermal stratification, decreases with the increase of water level, and increases with the increase of discharge flow; secondly, the effect of a temperature-control curtain on improving the outflow temperature is directly related to the thermal stratification in different months, and the improvement effect is better in spring and summer; finally, the improvement effect increases with the decrease of flow height above the temperature-control curtain, increases with the increase of water level, and decreases with the increase of discharge flow.

Fixed‐bed column adsorption of methyl orange by poly(vinyl pyrrolidone)‐functionalized manganese oxide

AbstractBACKGROUNDFixed‐bed column adsorption provides a practical approach for decontamination of wastewater from toxic azo dyes. A novel water‐stable poly(vinyl pyrrolidone)‐functionalized manganese oxide hydrothermally prepared for methyl orange azo dye adsorption is reported.RESULTSSurface studies of the composite were conducted using scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction and surface area analysis. The surface area of the composite (113 m2 g−1) was greater than that of plain metal oxide (108 m2 g−1). The point of zero charge was calculated using the salt addition method. A continuous flow of methyl orange was carried out in a 40 cm long glass column under different operating conditions determining the breakthrough curve and the breakthrough point time. Experiments were carried out as a function of initial dye concentration (10–30 mg L−1), bed height (0.6–1.5 cm) and rate of flow (5–20 mL min−1) from the column at constant temperature and pH.CONCLUSIONSThe saturation time increases from 700 to 3500 min with increase in bed length. The saturation time decreases from 2000 to 400 min with an increase in initial dye concentration. Similarly, when the flow rate is increased the saturation time and dye adsorption are reduced and the breakthrough curve becomes steeper. The adsorption data were evaluated using the Thomas model to calculate maximum adsorption at various flow rates and the Yoon–Nelson model to identify exactly the saturation point, confirming that the rate of reaction increases with increasing flow rate. © 2022 Society of Chemical Industry (SCI).

Numerical Modeling and a Parametric Study of Various Mass Flows Based on a Multi-Phase Computational Framework

Gravity-driven mass flows are typically large-scale complex multi-phase phenomena involving multiple interacting phases. Various types of mass flows usually exhibit distinct behaviors in their formation, propagation and deposition. In such large-scale geological systems, many uncertainties may arise from the variations in material composition and phase behavior. The present study aims to investigate the important characteristics of some common types of mass flows including debris flows, mudflows and earth flows, based on a recently developed multi-phase computational framework, r.avaflow for flow simulation. Fractions of different phases are varied to reflect different characteristics of material composition of various mass flows and simulate the resulting flow behavior. The evolution of the critical entities during the flow motion, such as velocity, peak discharge, flow height, kinetic energy, run-out distance and deposition is examined; considerable differences among various flows are identified and discussed. Overall, the simulated mudflow cases develop higher velocity, peak discharge, kinetic energy, and longer run-out distance than the debris flow cases. The fluid fraction has a significant influence on the flow dynamics; a higher fluid fraction often leads to higher velocities and long run-out distances, but lower kinetic energy, and it also affects the final deposition and deposition pattern considerably. The present study shows promising potential of a quantitative approach to the physics and mechanics of mass flows that may assist in the risk assessment of such large-scale destructive geological hazards or disasters.

Convolutional Neural Network and Optical Flow for the Assessment of Wave and Tide Parameters from Video Analysis (LEUCOTEA): An Innovative Tool for Coastal Monitoring

Coastal monitoring is a topic continuously developing, which has been applied using different approaches to assess the meteo-marine features, for example, to contribute to the development of improved management strategies. Among these different approaches, coastal video monitoring coupled with recent machine learning and computer vision techniques has spread widely to assess the meteo-marine features. Video monitoring allows to obtain large spatially and temporally datasets well-distributed along the coasts. The video records can compile a series of continuous frames where tide phases, wave parameters, and storm features are clearly observable. In this work, we present LEUCOTEA, an innovative system composed of a combined approach between Geophysical surveys, Convolutional Neural Network (CNN), and Optical Flow techniques to assess tide and storm parameters by a video record. Tide phases and storm surge were obtained through CNN classification techniques, while Optical Flow techniques were used to assess the wave flow and wave height impacting the coasts. Neural network predictions were compared with tide gauge records. Furthermore, water levels and wave heights were validated through spatial reference points obtained from pre-event topographic surveys in the proximity of surveillance cameras. This approach improved the calibration between network results and field data. Results were evaluated through a Root Mean Square Error analysis and analyses of the correlation coefficient between results and field data. LEUCOTEA system has been developed in the Mediterranean Sea through the use of video records acquired by surveillance cameras located in the proximity of south-eastern Sicily (Italy) and subsequently applied on the Atlantic coasts of Portugal to test the use of action cameras with the CNN and show the difference in terms of wave settings when compared with the Mediterranean coasts. The application of CNN and Optical Flow techniques could represent an improvement in the application of monitoring techniques in coastal environments, permitting to automatically collect a continuous record of data that are usually not densely distributed or available.

The effect of the elliptical front wall on energy conversion performance of the offshore OWC chamber: A numerical study

The configuration of the front wall has an obvious influence on the effect energy conversion effect of the offshore OWC devices. In order to improve the energy conversion effect of the OWC device, a new elliptic front wall structure for the offshore OWC chamber was proposed in this paper. The variation of pressure, outlet air flow and free surface height of the chamber were studied by numerical simulation, with the change in the angle of elliptical front wall (β = 0, 5, 10, 15, 20, 25, 30), and under the wave condition of relative wavelength L/B = 4.0–9.0. Based on the results, the effect of the elliptical front wall angle on the energy conversion efficiency of the offshore OWC chamber were analyzed. The main results are as follows: Compared with the rectangular front wall, the elliptical front wall can effectively improve the energy conversion effect. The elliptical front wall with β = 25 has the best comprehensive effect under the test wave condition. With the influence of it, the wave energy conversion efficiencyξ is about 25% higher than the chamber with the common rectangular front wall(β = 0). The results can be used as a reference for the design of OWC devices.

Reliability-based vulnerability analysis of bridge pier subjected to debris flow impact

In this paper, a finite element model of a highway bridge pier subjected to debris flow is established, which comprises a double-column pier, a gully channel, moving fluid and solid particles. By using the arbitrary Lagrangian-Eulerian (ALE) algorithm to calculate the fluid-solid coupling effect, the process of debris flow impacting on the pier is simulated. Based on the ‘two-phase flow’ theory, a simplified equation to calculate the impact force of debris flow containing both fluid and solid phases is proposed, and the variable parameters in the equation are determined through numerical simulation using the established FE model and the field-measured data. By comparing with the historical records of actual debris flows, the effectiveness of the numerical model and the proposed equation is verified. A reliability model of the pier subjected to debris flow is established, and the structural vulnerability is estimated by the MCS method. Using the site-observed data, the failure mode of a highway double-column pier subjected to impact of two-phase debris flow is studied. The critical velocities of debris flow causing the structure to have different modes of damage, and the critical impact height of debris flow on the pier suffering bending and shear failures are determined.

Effect of Boulder Size on Debris Flow Impact Pressure Using a CFD-DEM Numerical Model

Debris flows (DFs) are dangerous events that can cause the complete destruction of buildings and infrastructure, such as bridges; DFs therefore represent a high risk to public safety in exposed areas. The impact pressures due to these flows are essentially determined by the flow height, velocity and density, but other parameters that are less often considered are also involved. We developed a numerical model to evaluate the impact pressure of mass flows, focusing on a better description of the influence of the blocks transported in these flows: the block size strongly influences the impact pressure, which has a strong effect on structural damage. The numerical model proposed considers a staggered, loosely one-way granular–fluid coupling based on a distinct-element-method code, using the separate simulation results of a computing fluid dynamics code used to model the fluid phase. This model estimates the impact pressure distribution due to blocks at the local scale of the obstacle; the pressure due to the fluid phase can be added afterwards. The pressure applied by the DF increased with the maximum block size for a given set of DF characteristics: velocity, height and apparent density. The vulnerability of a given structure depends on the intensity of DFs: the pressure applied on the structure is one of considerable intensity. The existing vulnerability functions are interpreted in the light of the results obtained with the numerical model. This interpretation highlights the need to integrate new parameters in the intensity to better evaluate structures’ vulnerability to debris flows.

New Insights into the Estimation of Impact Load of Granular Flow against a Rigid Wall

The installation of a rigid wall is a main approach to mitigate a granular flow. The methods of the impact load against a rigid wall still remains a challenge. In this study, the progresses in the estimation of the impact load of granular flow against a rigid wall are introduced in detail. The influences of the slope angle, the installed angle of rigid wall, the volume of granular flow are not fully considered into the present models. The discrete element method is employed to reveal the effects of these factors on the impact load. The numerical results show that the volume of granular flow is a key factor to determine the evolution of the impact load on a rigid wall. The dynamic impact load of granular flow at the initial stage is decided by the angle between the rigid wall and slope surface. If the installation angle is same, the slope angle mainly determines the static load of granular flow. Based on these findings, we propose simplified model that the relationship between the impact load and the multiple physical parameters, such as slope angle, installation angle, repose angle, flow height and flow velocity, basal friction angle, and the volume of granular flow, is taken into account.

Erosion Process of Multiple Debris Flow Surges Caused by Check Dam Removal: An Experimental Study

AbstractDebris flows are one of the most serious natural disasters on Earth and cause great losses in human life and property each year. Check dams have been widely utilized in debris flow hazard mitigation, and over time, some control projects have exceeded their designed service lifetime. However, the processes of stored sediment erosion with multiple surges of debris flows after check dam removal are unknown. Here, the stored sediment erosion processes associated with different reductions in the dam height (i.e., the removed height) were revealed by physical experiments. The results showed that erosion was concentrated on the stored sediment scarp formed by dam removal and that the erosion process mainly included undercutting and widening. The erosion efficiency of the debris flow gradually decreased with the development of erosion and was positively correlated with removed height, negatively correlated with the accumulated debris flow volume, and proportional to the remaining potential volume of sediment to be eroded. The erosion volume development process was well described by an exponential function model, and the physical meanings of the parameters in the model and their empirical values were clarified. Moreover, the distribution of the erosion volume along the flume was shown to satisfy the Weibull distribution, and the distribution parameters were related to the removed height, erosion volume, and sediment volume fraction of the debris flow. We anticipate that our results will serve as a starting point for the demolition and reconstruction of debris flow hazard mitigation engineering in mountainous areas.

Rancang Bangun Monitoring Early Warning System Bencana Banjir Berdasarkan Ketinggian Aliran Sungai Mengunakan Modem SIM900 dan Internet of Things

The rainfall in the Cilacap region is high, about 80-100mm in October-March. The high rainfall that causes the overflow of river water is unpredictable. The high water discharge is not realized until the river water overflows and causes flooding. Therefore, a river water level monitoring system is needed to detect river overflows early. This tool uses a solar cell as a power supply. The monitoring system is divided into two points of river water level monitoring system with a distance between points for the laboratory scale stage, which is 100 meters. Sensors that measure the height of river flow are ultrasonic sensors. The sensor results are processed by microcontroller and SIM 900 L module to be sent to the database . When the water level is in the Alert level 3, the buzzer will sound as a warning. The ultrasonic sensor test results have a very small error. Sensor 1 has an average error of 0.00023% and ultrasonic sensor 2 has an error of 0.00016%. The system is able to transmit river water level data that can be accessed through the website .

Clinical parameters influencing the results of anterior rhinomanometry in children.

Nasal obstruction is a frequent symptom in both adults and children and it is a common reason to see an otorhinolaryngologist. Endoscopy of the nasal cavity and the epipharyngeal space along with anterior rhinomanometry is regarded the gold standard since many years to estimate the severity of nasal obstruction in the particular patient. Endoscopy shows anatomical reasons for an obstruction, whereas the nasal flow volume and nasal resistance can be determined using anterior rhinomanometry. Currently, there are only few data available for rhinomanometry results in children. The purpose of the present study was to evaluate the application of this technique in the pediatric population for objective evaluation of nasal flow. Whether it achieves reproducible results and which clinical parameters have some influence on the results were studied. 427 children (average age of 8.5years, range 7months through 17years) who were admitted to evaluate nasal patency or for allergy testing were examined. After clinical examination and endoscopy of the nasal cavity and epipharyngeal space, anterior rhinomanometry was performed before and after application of decongestant nose drops separately for each nose side in 334 children. The nasal flow with a pressure of 150 Pasc was measured and served for statistical evaluation. Flow values were correlated to clinical and endoscopic parameters along with results of allergy tests (prick tests). Reproducible rhinomanometric measurements were possible in children age 3years and older. However, the standard deviation and variation of measurements were significant in this cohort of patients. Statistically highest significant correlations were found between flow measurements and body height along with the age of the children (p < 0.01) and status following adenoidectomy (p < 0.05). No statistically significant correlations were found between rhinomanometry and results of prick tests. The study demonstrates that rhinomanometry can be applied in the pediatric population for objective evaluation of nasal obstruction and for determining the effects of decongestant nose drops. The highest correlation was found between nasal flow and children's body height, children's age and status following adenoidectomy. The correlation between nasal flow and clinically/endoscopically determined degree of nasal obstruction was lower. However, definition of normal flow values for particular age groups is challenging since the results showed high variation and standard deviation. Yet with regard to individual patient, the technique achieves reliable results in nasal provocation tests, which are widely used for allergy testing in children. When performed in children it should always be considered that there are age-specific requirements for the examination and interpretation of results in this patient cohort.

The impact of vent geometry on the growth of lava domes

SUMMARY Thick lava flows that are a feature of many volcanic fields on the Earth and Venus vary from sheet-like to nearly perfect axisymmetric domes. Here, we investigate how these geometrical characteristics depend on the shape of the feeder vent. We study the gravitational spreading of viscous lava erupting from elliptical vents onto a flat surface using 3-D numerical models. The aspect ratio of the vent, defined to be the major to minor axes ratio, varies between 1 and 25. In the limit of an aspect ratio of one, the vent is circular and spreading is axisymmetric. In the limit where the ratio is large, the vent behaves as a fissure. The numerical models rely on an isoviscous lava rheology and a constant volumetric eruption rate. In all cases, the initial phase of the dome’s evolution is in a lava-discharge dominated regime such that spreading is insignificant and the height of the dome increases at a constant rate over the vent area. For vent aspect ratios greater than five, three successive regimes of spreading are identified: 2-D spreading in the direction perpendicular to the major axis of the vent, a transient phase such that the dome shape evolves towards that of a circular dome and a late axisymmetric spreading phase that does not depend on the vent shape. These regimes are delimited by the times required for the flow thickness above the vent to reach a given height and for the flow to spread axisymmetrically up to a length equal to the semi-major axis of the vent. Numerical results for the flow height and runout length tend towards the similarity solutions in the 2-D and axisymmetric regimes. Two main implications for highly viscous (rhyolitic) fissure eruptions can be drawn. First, the fissure length determines the flow regimes. The longer the vent fissure length, the longer the early lava discharge regime and 2-D spreading perpendicular to the length of the fissure. Second, the aspect ratio of fissure-fed lava flows can be used as an indicator of the fissure length and the duration of lava discharge. The ellipticity of some terrestrial fissure-fed flows provides evidence for viscous gravity-driven spreading terminated before the onset of the axisymmetric regime. On the other hand, the circular domes on Venus appear to be the result of fissure-fed eruptions sustained enough for the spreading to reach the axisymmetric regime. We propose relationships providing estimates of the fissure length and the duration of lava discharge based on fossil dome dimensions.

The investigation of the average diameter of the SiO2 nanoparticles effect on the oil displacing efficiency from the pore in the rock formation using nanosuspension as a displacing agent

The numerical investigation of the nanofluid flow, which displaced the oil, in a microchannel was carried out. The effect of the average diameter of the SiO2 nanoparticles on the oil displacing efficiency by nanofluids for different sizes of microchannel at various Reynolds numbers was studied. A T-shaped microchannel with a vertical channel, called a pore channel, which imitated the pore in the rock formation was considered as a computational domain. The main flow channel width and height were 200 µm. The width and height of the pore channel were varied in the range from 100 µm to 800 µm. The Reynolds number varied from 0.1 to 100. The oil recovery coefficient, which is defined as the ratio of the displacing volume of oil from the pore to the volume of the pore was considered as the main studied characteristic. The nanofluid is considered a single-phase fluid with experimentally obtained properties. The mass concentration of SiO2 nanoparticles was 0.5%. The average diameters of nanoparticles were 5 nm, 18 nm, and 50 nm. It was found, that the oil recovery coefficient increased with a decrease in the average diameter of nanoparticles. It was obtained that the nanofluid can enhance the oil recovery several times compared to pure water.

Relationship between First Order System and Transient Response of Separation Height of Flow Induced by Plasma Actuator with Burst Modulation

Relationship between First Order System and Transient Response of Separation Height of Flow Induced by Plasma Actuator with Burst Modulation

Tailings Dam Break: The Influence of Slurry with Different Concentrations Downstream

The risk of tailings dam-break disaster is dependent on the type of slurry and its flow characteristics. The flow characteristics of slurry surging from tailings dams collapse are directly influenced by grain size, breach width, slurry concentration, and surface roughness of the gully. Among these parameters, slurry concentration plays the most critical role, but there are few studies on it. This paper focuses on the flow characteristics of slurry with different concentrations, and a series of flume experiments were carried out to obtain the flow characteristics of inundated height, impact force, and velocity in 30%, 40%, 50%, and 60% concentrations. The study confirms that the concentration of slurry has a significant influence on the flow characteristics. Through the experimental study, it is observed that, with the decreasing of slurry concentration, the impact force and velocity of slurry increased in varying degrees; on the contrary, the flow height elevated with the slurry concentration decreasing. The main reason is that the higher the slurry concentration, the higher the static yield stress and viscosity—in varying degrees. The results can provide a detailed understanding of the slurry concentration influence on the flow characteristics, which guides the evacuation time and height downstream.

Effect of Upstream Dam Geometry on Peak Discharge During Overtopping Breach in Noncohesive Homogeneous Embankment Dams; Implications for Tailings Dams

AbstractTailings dams differ from conventional water‐retaining dams in design, materials retained behind the dam and used in construction of the dam, and the inclination of the upstream face of the dam. In this paper, we isolate the effect of upstream slope angle on behavior during overtopping breach. Six 1 m high homogeneous fine sand dams were constructed with upstream slope angles varying between 10.0° and 30.0° and brought to failure by V notch overtopping. Slope angle was observed to define the height of flow over the erosional breach crest hydraulic control structure that forms in the upstream face of the dam, with higher peak outflow corresponding to steeper upstream slope angles. A semiellipse was observed to be an excellent approximation of the geometry of the breach throughout the rising limb of the hydrograph to peak outflow. This observation permitted the use of the Ramanujan approximation for perimeter of an ellipse to define a mathematical relationship between breach width and arc length. A simplified method to predict the rising limb of the outflow hydrograph was then proposed based on the assumption of linear growth of breach width coupled with a semielliptical breach geometry. These findings show that hazard analysis for overtopping failure should consider the effect of upstream slope angle on peak outflow.

Heat transfer enhancement using double taper microchannel

A three-dimensional numerical study on the combined effect of height as well as width tapering on the thermal performance of double taper microchannel is presented in this paper. The channel inlet width is considered as 300 µm, taper ratio on sidewalls and bottom wall are varied from 0 to 1 and 1 to 3.9, respectively. The thermal resistance ratio, average bottom wall temperature, temperature difference ratio, and pumping power ratio of the channel are evaluated for various flow rates, height, and width tapering. Results showed higher reduction of wall temperature with combined effect height as well as width tapering compared with straight channel. The optimal size of the micro channel to minimize the pumping power and average wall temperature on the constraint of heat flux and footprint area is found. The reduction in average bottom wall temperature is 17.34%, and pumping power ratio is 0.44 (56% power reduction) noted, respectively, at Reynolds number 340. Finally, optimal dimension of double taper microchannel is evaluated for better thermo-hydraulic performance.

Turbulent flow height measurement with stereo vision

This paper describes the process of 3D analysis of two water currents with method of photogrammetry. Photogrammetry is used in fields such as architecture, engineering, police investigation, preserving cultural heritage, military and geology. This method can be used in military to reconstruct a site with traces of shrapnel or various projectiles. In our case we tried to measure height of turbulent flow, where two currents collided at the angle of 90°. In first section we introduce our problem and method. Second section describes method of photogrammetry and basics of torrential flows. In third section we describe our experiment. Fourth section describes the course of getting 3D model. In fifth section we analyze results and in sixth section, a conclusion is given.