Open Water Tank Research Articles

Analysis of drinking water quality based on biological, physical and chemical parameters in Lekobalo Village, Gorontalo City, Indonesia

Abstract. Katili L, Baderan DWK, Kumaji SS. 2023. Analysis of drinking water quality based on biological, physical and chemical parameters in Lekobalo Village, Gorontalo City, Indonesia. Intl J Bonorowo Wetlands 13: 22-29. Lekobalo Village is a part of the Gorontalo City, Indonesia area, which has not yet received full clean water coverage. Therefore, the community in Lekobalo used the wellsprings as the source of drinking water. An open water tank around the wellspring has been the source of drinking water for people in the surrounding. It becomes a place for household chores such as bathing, doing laundry, and serving as a lavatory. That makes the place look messy due to the household waste around the wellspring, which decreases the drinking water quality there. Hence, a test of the drinking water in Lekobalo is crucially needed. This study is descriptive-qualitative research that was conducted by a direct survey. Sample collection was conducted using sterilized bottles from the laboratory, and the data obtained were analyzed descriptively. This study aims to determine drinking water quality based on biological, physical, and chemical parameters. The research revealed that the quality of drinking water in Lekobali based on the biological parameter was considered polluted by Escherichia coli and coliform bacteria. The findings revealed that the average score of E. coli was 10.3 MPN/100 ml and coliform 200.5 MPN/100 mL. In physical parameters, the drinking water quality is relatively good with an average temperature of 20°C, turbidity NTU, scentless, tasteless, and colorless. The drinking water criterion that did not meet the physical parameters is the TDS (Total Dissolved Solid), which is 1,525 mg/L. According to the chemical parameter, the quality of the drinking water is considered relatively good with some average score of arsenic (As) 0 mg/L, fluoride (F) 1 mg/L, nitrite (NO2) 0.02 mg/L, nitrate (NO3) 3.6 mg/L, iron (Fe) 0.12 mg/L, Power of Hydrogen (pH) 6.6 mg/L and manganese (Mn) 0 mg/L. The chemical parameters that did not meet the standard qualification of drinking water based on the chemical parameters are chromium (Cr), and cadmium (Cd), as the average scores are 0.34 mg/L and 0.047 mg/L. This study can be used as one of the government's databases as an input in developing programs and activities to improve drinking water quality and control water pollution.

Dispersal Movements and Hot Spot Areas of Juvenile Bonelli’s Eagles on the Island of Crete, Greece

The Bonelli’s Eagle (Aquila fasciata) is the main avian predator in almost all the islands of the Greek archipelagos. The phase of its natal dispersal has never been studied in Greece, though it constitutes a crucial part of the species ecology and conservation. In an effort to investigate the movement patterns and settlement areas of young eagles, we tagged 30 fledglings on the island of Crete during 2019–2023 with GPS/GSM transmitters. Fledging date was set the first day with full satellite coverage and consecutive GPS fixes for individual birds while the initiation of the dispersal period was established when they performed consecutive long flights, overstaying away from their natal territory (>10 km). Mean fledgling date was calculated at May 27 (range = 20/5–8/6), whereas the dispersal period started on average on September 03 (range = 30/8–21/9), namely ca. 90–100 days after the abandonment of the nest. All juvenile birds wandered around over the entire island residing primarily in two distinct habitat types i.e. coastal cliffs and satellite islets around Crete and agricultural areas in the lowlands covered with olive groves and vineyards. Preliminary surveys show that the juvenile birds avoid active Bonelli’s Eagle territories and select rural areas near landfills, water reservoirs, fowl pens, and uninhabited islets, specializing on prey species that are readily available (i.e. gulls, corvids, rock pigeons, wild rabbits and poultry). This fact makes them particularly susceptible to human-induced mortality such as electrocution, drowning in open water tanks and poaching, which accounted for ca. 60% of the casualties of this age group. Overall, the study confirms that land use changes and human pressure are the major threats for the species on Crete, likewise in the rest of its distribution range in the Mediterranean.

FLUID FLOW INDUCED BY AN ELASTIC PLATE IN HEAVING MOTION

We perform three-dimensional simulations of an elastic plate heaving in a sinusoidal motion with different frequencies to explore the effects of the forcing heaving frequency on the hydrodynamic force generation and flow structures. It is aimed to simulate the motion of a rectangular elastic plate, representing a simplified flexible wing or fin, placed in an open water tank as in a corresponding experimental study. The top edge of the plate oscillates sinusoidally in water at rest. Simulations are conducted for the fluid structure interaction of an elastic plate with a special version of the open-source library C++ OpenFOAM, foam-extend-3.2. The plate oscillates at different heaving frequencies in a range of 3.5 Hz and 4.5 Hz. Experiments are carried out to validate our simulations. The results are in a good agreement with the experiment in terms of the representation of the resonant frequency and the induced hydrodynamic forces. It is found that the hydrodynamic force and propulsive efficiency are mainly affected by the elastic deformation and forcing heaving frequencies. The generated thrust is observed to be significantly enhanced at the resonant frequency, while the propulsive efficiency is increased at the heaving frequency which is greater than the resonant frequency. The results of our simulations point to the importance of resonant flapping frequency for considering the optimal heaving frequency to achieve the best performance and to get the improved thrust force, which are crucial for the locomotion of birds, insects, fishes, flapping-based micro air and underwater vehicles.

Tools and Techniques in Preparation of Coloured Bones and Skeletons for Effective Teaching, Learning and Museums

Background: Teaching veterinary osteology and arthrology has been performed with free bones collected from various animals after processing and preserving them for long duration. The profession of teaching Anatomy to undergraduate and postgraduate students in veterinary colleges not only requires the knowledge on Veterinary Gross Anatomy but also the methods of preparation of specimen for laboratory use. This article explains the methods and steps in preparation of coloured skulls, bones of forelimb, hindlimb, rib cage, digits and whole mounted skeletons, to be used in the anatomy laboratory to increase the efficiency of both teaching and learning. Methods: A carcass of adult horse donated by a farmer was utilized for making complete coloured skeleton. The bones were collected from the carcass by natural maceration technique followed by cleaning with mild chemicals. The metallic paints and commonly available tools were used for colouring and mounting of horse skeleton. The parts of bones viz. process, fossa, articular area, foramen, the origin and insertion of various muscles were prepared with colours and labels on the surfaces of bones for teaching and museum purpose. The sequential step by step procedure for skeleton preparation in quickest possible time was standardized and explained using various tools. Result: The natural maceration in open water tank was found to be most effective way of maceration of carcasses for collection of bones with their normal colour. The bones were processed mainly with washing soap powder and calcium carbonate followed by drying in natural sunlight which increased the brightness of the bone without any damage to the structure. The coloured skulls, bones of forelimb, hindlimb, rib cage, digits and whole mounted skeletons were prepared with available tools and chemical as this work consumes less time and cost and increases the students’ learning efficiency, which will also be an asset and center of attraction for any Institution.

The Study of Effective Methods for Cleaning of Contaminated Water and Soil, Participation of Natural Radionuclides in the Processes Occurring in the Plant Mass

A comprehensive physical, chemical and microbiological analysis of water, vegetation and soil samples taken from regions of the country was carried out. The distributions of heavy metals, trace amounts of natural radionuclides and other inorganic components in environmental objects were studied. By systematic studies have established that the degree of assimilation of the K40 isotope by green plant mass from water and soil is about 7-10 times higher than the degree of assimilation of radioactive isotopes of other elements. The K40 radioisotope is identified in all environmental objects. Initiation of the process by ionizing radiation and further elementary reactions of active particles creates the real condition for the highly endothermic processes of dissociation of water and carbon dioxide molecules, synthesis of new organic molecules and molecular oxygen. The role of gamma radiation of K40 radioisotope should be taken into account at comprehensive analysis of initial stage of photosynthesis. This conclusion is consistent with the revealed facts of increased plant yields on soils with relatively high concentrations of natural radioisotopes, observation of photosynthesis under thick layers of water in the presence of only long-wave infrared rays or in the absence of chlorophyll and oxygen. The cleaning method of soil contaminated with heavy metals and radionuclides have been studied, and the method for the physical adsorption and chemical sorption of organic pollutants (oil products) on the surfaces of wood cheeps floating in open water tank irradiated with ionizing rays has been developed.

An experimental platform of variable speed pumped storage unit under wave disturbance: introduction and preliminary progress

The importance of pumped storage plants (PSPs) is continuously increasing in power systems with more and more variable renewable energies. For the research and development of PSPs, variable speed technology and sea-water PSP are two important new orientations. In this paper, an experimental platform of variable speed pumped storage unit under wave disturbance is introduced. The purpose of the platform is to study the design and operation mechanism of variable speed PSP based on various common technical problems, especially for the four aspects: transient processes, variable speed unit, coordination control, wave disturbance. The platform adopts a Chinese sea-water PSP in feasibility stage as the prototype, and a model scale of 1:4 is applied. It consists of nine sub-systems, including waterway system, variable speed reversible model unit, circulating water system, speed governor system, AC excitation and electric protection, coordination control, monitoring system, intelligent AC load and measurement system. The model unit contains a reversible pump turbine, a doubly fed induction machine, etc. The speed variation range is ±8%, and the rated power is 78.13 kW. The model runner meets the IEC standard with a reference diameter of 284.3 mm. The upstream water tank is a closed pressure tank that can adjust the pressure and discharge. The downstream water tank is an open water tank that can simulate wave level fluctuation. Regarding the control system, it has four core parts: local control unit, speed governor, converter and coordination controller. The experimental study content contains three key aspects: (1) performance validation for variable speed unit; (2) operating stability under complex disturbances; (3) capability of variable speed PSP during transient processes. The experimental study based on the platform aims for laying a theoretical and technical foundation for the follow-up construction and operation of real sea-water PSPs with variable speed units.

Outbreak investigation and a case control study of Dengue fever at Rawalpindi, Pakistan during July to September 2019

Background: Dengue is one of the most prevalent vector born disease and has been a major public health threat since 2005 in Pakistan. It has been added in list of notifiable diseases since 2007 in Pakistan. It is caused by any of its four virus species so a person can be infected with a dengue virus as many as four times in his or her life. A dengue mosquito takes 8 to 10 days from an egg to an adult. The objective was to confirm the outbreak, identify possible risk factors and to formulate recommendations for immediate control and future prevention. Methods and materials: Study design A descriptive study followed by case control study. Methodology Active case finding through house to house search was conducted by surveying 540 houses from 29th August till 5th September 2019. A spot Map was made. Tool to collect information was a semi structured Questionnaire. A Case was defined as any person having high grade fever for more than 2 and less than10 days along with any two of the following signs and symptoms:headache,retro-orbital pain, myalgia, arthralgia, epistaxis, hematemesis, melena, hemoptysis, vomiting or abdominal pain residing in Gulbahar Scheme, during 7th August to 5th September 2019. Results: During active case search 104 confirmed cases of dengue fever were identified, effecting all age groups from 3 to 78 years. Most effected age group was 31 to 40 years, 30.76%. Most effected gender was male 62.5%.Age Specific attack rates were calculated. Risk factor analysis revealed most probable causes of spread was presence of water bodies in the area (OR 0.196%), water storage in houses (OR 1.00%), exposure to other cases (OR 0.44%), and under construction houses. Conclusion: Major causes of this outbreak include extensive rains this year leading to pooling of rain water at uneven areas and construction sites. Many under construction houses and vacant plots serving as garbage dump and water pools. Non Availability of proper water drainage system in the area. Uncovered water storage in houses and open water tanks on roofs. Not much protective measures and routine IRS.

Herbicide treatment alters the effects of water hyacinth on larval mosquito abundance.

Invasive aquatic weeds are managed with herbicides to reduce their negative impacts on waterways in many areas, including the California Delta Region. Herbicides create a dynamic environment of living and decomposing plant matter that could affect larval mosquitoes and other invertebrates, such as their predators and competitors. Our objective was to compare the number of larval mosquitoes in water or water hyacinth, before and after an herbicide treatment. We created replicated pond mesocosms with water hyacinth, water hyacinth treated with glyphosate and an oil adjuvant, open water, and water with glyphosate plus adjuvant. We sampled for larval mosquitoes and other aquatic invertebrates. Before herbicide addition, there was a trend for more larval mosquitoes in open water tanks than in tanks with water hyacinth. Herbicide application resulted in an immediate decrease of larval mosquitoes. As decay progressed, larval mosquitoes became most abundant in mesocosms with herbicide-treated hyacinth and very few larval mosquitoes were found in other habitat treatments. Although the numbers of predatory and competitor insects had some variation between treatments, no clear pattern emerged. This information on how invasive weed management with herbicides affects larval mosquitoes will allow control practices for larval mosquitoes and invasive weeds to be better integrated.

Panel measurement method for the determination of scattering coefficients and edge diffraction in an open water tank.

Material effective properties of composite media or their acoustic performance are often required to be experimentally determined or verified. For underwater applications, systems can be characterized in an open water tank in which a conventional measurement configuration consists of the panel, an acoustic source, and two hydrophones, one on either side of the panel. However, panel measurements may be greatly complicated by waves diffracted by the panel edges. The three-point method is a technique that decomposes total pressure into contributions of the incident, reflected, transmitted, and edge-diffracted pressures. These contributions are determined using measurements at three positions. Reflection and transmission coefficients can then be obtained by removing the contribution of the edge-diffracted waves. The three-point method is applied to an aluminum reference panel for which the experimental scattering coefficients are in very good agreement with those of an infinite panel. The validity limits of the method are also studied. Finally, a pressure mapping shows that the three-point method leads to an accurate determination of the reflection and transmission coefficients for different positions despite strong variations of the edge-diffracted pressure.

Review for prediction of evaporation rate at natural convection

The aim of the present research is to analyse evaporation intensity induced by natural convection. Simultaneous heat and mass transfer is observed in the case of evaporation from open water tanks as well as during the evaporation of surface moisture when drying materials. Relationships to determine the evaporation rate at natural convection were collected within this work. The equations for evaporation rate from these studies are valid in different ranges of interpretation (different gas and liquid temperature, surface area) and under certain conditions, which reduces their usefulness. New measuring apparatus has been installed and equations for determination of evaporation rate were validated. As a result of the validation, the equations of Leven, Boelter et al. and Bower and Saylor proved to be the most precise (±5% deviation) and equations of Box showed ±10% deviation to our measurement results.

A New Device for Pressure Control and Energy Recovery in Water Distribution Networks

The potential energy of the water in Water Distribution Networks (WDNs) usually exceeds the amount needed for delivery and consumption and, at the present time, it is mainly dissipated through Pressure Reducing Valves (PRVs) or Open Water Tanks. The present study suggests the use of a new energy-producing device, a Cross-flow turbine with positive outlet pressure named PRS (Power Recovery System), which can provide the same service as PRVs and water tanks, with additional significant hydropower production. After a short presentation of the PRS, the management rules of the proposed device are laid out, according to two possible modes. In the ‘passive’ mode, the piezometric level downstream of the turbine is fixed at the sought after value, in the ‘active’ mode, the discharge is regulated according to the required value. The design criterion is then presented, based on a simple relationship linking dimensionless numbers. A PRS is finally designed for a typical water distribution network, serving the city of Palermo (Italy). The resulting cost-benefit analysis is compared with a similar one carried out in previous work for a regulation system based on the use of a Pump As Turbine (PAT). The comparison shows the improvement obtained by the use of the PRS, consisting of higher energy production, as well as lower construction and installation costs.

Evaporation reduction from open water tanks using palm-frond covers: Effects of tank shape and coverage pattern

The limited fresh water resources and increasing future demand for water necessitate the importance of optimum use of water; especially in arid/semi-arid regions. The purpose of this study is to examine reducing evaporation losses from open water bodies using palm-frond sheets as cover material. Four open constant-depth water tanks with two different surface areas have been used in the study. The tanks had square and rectangular surface areas. The tanks were covered with two patterns of palm-frond sheets: a) staggered strips-no strips covering half of the surface area (strips-covered), and b) single sheet covering half of the surface area (½-covered). Data of cumulative evaporation depths were recorded daily continuously from the covered tanks, as well as from the uncovered tanks, to assess the relative efficiency of evaporation reduction. The results indicated that the strips-covered pattern outperformed the ½-covered; it reduced the evaporation depth by approximately 20% and 24% for the square and rectangular surface tanks; respectively, when compared to the ½-covered pattern. Moreover, the strips-covered pattern resulted in approximately 76% less evaporation depth compared to the uncovered reference tanks. Additionally, water quality analyses showed that such palm-based cover materials have insignificant effect on the water quality. These results confirmed that evaporation can be reduced and controlled using environment friendly safe techniques.

Standardized Comparison of Prostate Morcellators Using a New Ex-Vivo Model

Transurethral laser enucleation of the prostate is a common therapeutic option for the treatment of benign prostate enlargement. Evacuation of the enucleated tissue from the bladder is usually performed by electric morcellators. Until now, a standardized evaluation of the different morcellator settings does not exist. Therefore, we developed an ex-vivo model to find the best settings for four different morcellators. We morcellated pieces of a prostate adenoma after an open adenomectomy. The same speed settings were used to morcellate commercially available minced meat, fine pork sausage meat, and bovine heart, all of which had been cooked for 10 minutes using a Piranha Morcellator. We also morcellated raw pig perirenal fat tissue, raw pig liver, and raw bovine heart. The pieces were morcellated at different speed settings in an open water tank filled with saline. Because raw bovine heart showed to be the most equivalent tissue, we morcellated five pieces with four different settings of four different morcellators: The Piranha, the VersaCut, and two morcellator prototypes. The median retrieval rate for the prostate adenoma was 14.02 (3.7-19.8) g/min. The retrieval rate for raw bovine heart was 13.75 (5.66-20) g/min. The maximum morcellation rates of the morcellators were: Piranha 20 (19.3-21.4) g/min, VersaCut 10.8 (8.2-13.1) g/min, Karl Storz prototype 9.8 (7.9-10.76) g/min, and Richard Wolf prototype 38.6 (35.3-42.9) g/min. Raw bovine heart tissue is suitable for ex-vivo testing of prostate morcellators and can replace human prostate tissue in this standardized setting. In our ex-vivo study, the morcellation rates of the different morcellators increased with optimized oscillation speed and suction power settings. This needs to be confirmed in clinical studies.

Flow Structure of a Coaxial Circular Jet with Axisymmetric and Helical Instability Modes

The flow structures in a coaxial jet with axisymmetric and helical instability modes for a comparatively low Reynolds number were investigated. The flow visualization and the measurements of velocities were carried out in an open water tank. In addition, three-dimensional numerical simulation of a coaxial jet was also performed using the commercial CFD software FLUENT 6.3. It was confirmed that the helical vortex was shed for the range of ratios of velocity of the inner to that of the outer jet from 0.5 to 1.0. Two characteristic flow regimes, i.e., axisymmetric and helical instability modes, were simulated in the flow field. For the coaxial jet with helical instability, the axial velocity along the centerline of the jet decreased more than that of the coaxial jet with axisymmetric instability. The axial velocity fluctuation at the centerline of the jet was small near the nozzle exit. However, the radial velocity fluctuation at that location increased. The convection velocity of vortices in the inner shear layer was larger than that for the outer shear layer. The convection velocity of vortices with the helical instability was slightly larger than that of the vortices with the axisymmetric instability. Consequently, the variation of velocity fluctuations and the convection velocity was associated with the arrangement of the vortex street in the shear layer.

Experimental and Numerical Study of Laminar Round Jet Flows Along a Wall

In the present study, both experimental and numerical techniques were employed to study three-dimensional laminar wall jet flows. The wall jet was created using a circular pipe of diameter 7×10−3 m and flows into an open water tank. The inlet Reynolds numbers based on the pipe diameter and jet exit velocity were 310 and 800. A particle image velocimetry (PIV) was used to conduct detailed measurements at various streamwise-transverse and streamwise-spanwise planes. The complete nonlinear incompressible Navier–Stokes equation was also solved using a collocated finite volume based in-house computational fluid dynamics (CFD) code. The computation was performed for three inlet Reynolds numbers, namely, 310, 420, and 800. From the PIV measurements and CFD results, velocity profiles and jet half-widths were extracted at selected downstream locations. It was observed that the numerical results are in reasonable agreement with the experimental data. The distributions of the velocities, jet spread rates, and vorticity were used to provide insight into the characteristics of three-dimensional laminar wall jet flows.

Flow Visualization and Characteristics of a Coaxial Jet with a Tabbed Annular Nozzle

Flow visualization and measurements of mean and fluctuating velocities were performed on a coaxial jet with a velocity ratio of 0.6 at a Reynolds number of 3 000 in an open water tank using hot-film anemometry, particle image velocimetry (2D and stereoscopic PIV) and laser-induced fluorescence (LIF). Axisymmetric and streamwise vortical structures were revealed in the near-field of the coaxial jet. The annular nozzle has six vortex generators in order to enhance the streamwise vortices generated in the mixing layer. Furthermore, the annular jet was excited by a shaker in order to enhance the axisymmetric vortices. For the tabbed coaxial jet, jet spreading downstream was greater than for the jet without tabs. The cause of the entrainment increment is the development of axisymmetric and streamwise vortex structures. In the case of excited jets, significant axisymmetric and streamwise vortical structures develop, and the jet width expands from the exit nozzle. Consequently, the flow rate of the excited jet with tabs is larger than that of the unexcited jet without tabs.

Interpreting the Blue Sharks at Underwater World

Interpreting the Blue Sharks at Underwater World Essay by Ryder W. Miller San Francisco, California, USA October 2nd, 1998: It was an exciting night at Underwater World, one filled with surprise and elation. There was a special, special treat: the surprise arrival of the Blue Shark. The sleek animal made its way around the open water tank, negotiating the long, narrow and crowded space. It was more beautiful than the other sharks in the tank, with gorgeous shiny blue skin on top and pure white skin underneath. The first was joined by a second six days later. At the time, they were the only Blue Sharks on display in the country. As an interpreter/naturalist at Underwater World in California (now called the Monterey Bay Aquarium), I had heard rumors that a Blue Shark was to be introduced, but I gave up on those hopes when I was discouraged by others in the husbandry department, some of whom said it was not possible and wouldn't happen. The husbandry staff acquires the fish, and they are the fish doctors. They also clean the tanks and feed the fish. The interpretive/naturalist staff at the aquarium help the visitors appreciates and understands the fish and the exhibit. Sometimes the husbandry staff surprises the naturalists with an introduction into the tanks, which keeps the naturalists excited about going to work each day. A shark in captivity provides an opportunity to work for marine conservation, but there are potential problems as the public may have difficulty seeing animals in captivity. Interpreters at aquariums and zoos have to be prepared to explain the rationale for why an animal is kept in captivity. Questions can come up about how well they are being taken care of, and if they like being in captivity. Interpreting sharks is also controversial because many people are still fearful of sharks due to old misunderstandings. Visitors often ask if we have Great White Sharks at the aquarium and we also need to explain why we don't. Animals serve an important role in zoos and aquariums, but interpreting them can be slippery with a public that has seen both or either movie Born Free or Jaws. I will be your guide for this tale about the Blue Sharks at Underwater World, which will show you how to bypass some of the potential problems of interpreting sharks in captivity in particular, but animals in captivity in general. I will also try to add the perspectives of ecology and aesthetic appreciation which can sometimes be more interesting than the dry facts about fish's ages, ranges, sizes and food preferences. I will also show you how to challenge visitors, as an activity, to look at things from a fish's (a

Flow visualization of vortex structure of an excited coaxial jet

This paper describes the results of experimental and numerical studies concerning the near-field vortical structure and dynamics of a coaxial jet. The effect of excitation of annular and circular jets on the vortical structure in the inner and outer shear-layers was studied. The flow visualization and the measurements of mean and fluctuating velocities, by a hot-film probe and the particle image velocimetry (PIV) technique, were carried out in an open water tank. The results of flow visualization and numerical simulation are in good agreement. With the excitation of a half of the initial vortex frequency, it is found that the vortex-pairing event is promoted by the forced excitation and it results in the rapid expansion of the jet width and the increase of velocity fluctuation and the entrainment rate. For the velocity ratio near unity, the dominant peak frequency coincides with the initial vortex frequency, i.e., the lip wake vortex frequency, independent of the forced excitation frequency.

1935 同軸水噴流の渦構造に及ぼす外側・内側噴流加振の影響

This paper describes the results of experimental studies concerning the near-field vortex structure and dynamics of a coaxial jet. The effect of excitation and circular jets on the vortical structure in the inner and outer shear-layer was studied. The flow visualization and the measurements of mean and fluctuating velocities by a hot-film probe and the particle image velocimetry (PIV) technique, were carried out in an open water tank. For the excitation of the initial vortex frequency, it is found that the vortex-pairing event is promoted by the forced by the forced excitation and it results in the rapid expansion of the jet width and the increase of velocity fluctuation and the entrainment rate. It is certified that the vortex-pairing event in the shear-layer is affected by the excitation of the relevant jet. For the velocity ratio near unity, the dominant peak frequency becomes the initial vortex frequency independent of the forced excitation frequency.

Gravity-driven countercurrent two-phase flow during filling of an unvented vessel

Countercurrent two-phase flow associated with filling of sealed vessels via gravity-driven liquid injection through inclined channels was experimentally studied and analytically modeled. Experiments were performed using transparent tubular test sections connected at one end to the bottom of a large, open water tank, and at the other end to an unvented tank. The test section parameters (including the channel diameter (1.27–2.54cm), length (30.5–122 cm), angle of inclination with respect to horizontal plane (0–30°), and the empty volume in the sealed vessel) were systematically varied. Flow regimes in the test section were recorded and transient flow rates were measured during the experiments. Oscillatory, and intermittent stratified slug, were dominant flow regimes in most tests. The quasi-steady liquid superficial velocity in the test section was sensitive to the test section dimensions, and varied in the range 0.04–0.95 m s −1. These flow regimes were mechanisally modeled. The models are shown to satisfactory predict the measured hydrodynamic parameters.