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Intake is an open channel that usually has a non-uniform flow along its length. The pattern of the flow in lateral intakes is fully three-dimensional. That is why many studies were carried out on the flow characteristics at the intakes. Velocity and direction change in lateral intakes lead to non-consistency and recirculation of the flow. As the result of these whirlpools, depositions are accumulated inside intakes which consequently decrease intake efficiency. High maintenance cost is regularly paid in order to dredge the sedimentation areas and to guarantee and maintain efficiency. The aims of this study were to get a suitable design of the lateral intakes to improve the flow characteristics at junctions. This study is conducted by using a numerical Software Delft3D-FM which used in predicting flows pattern which validated and employed in a parametric study. The model dimensions were assumed based on a real project data at Nile River in Assiut, Egypt. In this study, four models with sharp edges and different bed levels were presented to investigate flow separation zones at different angles of the intake entrance. In order to control the model accuracy in predicting the dimensions of the separated areas, the results were compared with the base configuration which has a flat horizontal bed level of intake. Comparisons between the predicted and the initial configuration velocities at the considered sections indicate that the model captures most of the trends with sensible accuracy. It is concluded that configuration number 4 which has two-fold baffle walls located on the right side has a significant effect on improving flow velocity, circulation zone length, reverse flow width as it enforces the flow to the inner side achieving a good flow distribution inside the intake. The results indicate also that the optimal angle of lateral intake which gives minimum length and width of separation zone is at θ = 30°. [ABSTRACT FROM AUTHOR]

From space, the Pacific glitters in ocean blue. What might the world's largest ocean contribute to missio Dei? A spiral methodology is used to trace connections between the baptism of Jesus, early Christian art, recent legal (Treaty of Waitangi Tribunal) research and indigenous knowing, including ocean voyaging, ancestor understandings of whirlpools, Māori water rites and oral history of river beings (taniwha). The argument is that indigenous Oceanic (Māori) understandings of water, in conversation with baptismal narratives, present missio Dei as an immersion in God. Mission is located not in the activity of the church – and hence mission expansion as part of European colonisation – but in the being and becoming of God. Creation and redemption are interconnected and an environmental ethic is expected. Children of the waters (ngā tamariki o te Moana nui a Kiwa) listen to creation's voice (taniwha speaking) and act for the life (waiora) of water. [ABSTRACT FROM AUTHOR]

The velocity and structure of the Lomonosov Equatorial Undercurrent of the Atlantic Ocean are determined based on the data measured with a shipborne acoustic profiler from 2014 to 2017. The seasonal variability of this flow is estimated, and the cases of its outcropping to the surface in the spring of the Northern Hemisphere are revealed. [ABSTRACT FROM AUTHOR]

Unbaffled stirred tanks are characterized by a highly swirling fluid motion and, unless they are completely filled and closed with a lid, a central whirlpool takes place, whose depth depends on the impeller rotational speed. In some cases, periodic rotating waves appear, regardless of the axial symmetry of the system. These waves may result into undesirable periodic stresses for the structure, the vessel and the process connections. In this paper, a comprehensive experimental study on the onset and the characterization of periodic free-surface oscillations in unbaffled stirred vessels is carried out. Different wave shapes (or oscillation modes) may be observed, depending on the operating conditions. The oscillation mode of the free liquid surface is experimentally evaluated by both visual observation and measurements of the local dynamic pressure time traces. The oscillation frequency is identified from the time traces by means of simple Fast Fourier Transform. The natural frequency of each oscillation mode is in excellent agreement with predictions obtained by the theory of sloshing in case of still liquids in cylinders, but the effect of impeller is here analyzed in detail. Several experiments using different tank geometries, filling ratios and liquid viscosities were carried out. In all cases, the observed frequency was found to increase linearly with the impeller speed, with a slope that depends on the impeller geometry and on the oscillation mode under analysis. A simple predictive model is developed and validated by comparison with experimental data. [ABSTRACT FROM AUTHOR]

A non-linear, uniformly stratified ocean model is used to investigate the stability and existence of perturbed rotating whirlpools that represent a certain class of exact solutions for the governing nonlinear equations describing the propagation of internal gravity waves in stratified media. A cut-off frequency γ is identified, beyond which the flow is completely stable to linear disturbances. An analysis close to cut-offs reveals the latitude-dependent distribution of eigenfrequencies of oscillatory and evanescent perturbations of whirlpools. [ABSTRACT FROM AUTHOR]

We report on the observation of the polygonal whirlpools in the thin layer of ferrofluid under illumination with a laser beam carrying optical vortex and in the presence of a vertical magnetic field. This kind of structures have attracted attention after discovering a hexagonal storm in Saturn's atmosphere. Our polygonal whirlpools were created in a closed system (no free surfaces) in micro-scale (whirlpool diameter <20 µm) by the use of holographic optical tweezers. The polygonal shape was changed by varying the magnetic field strength or value of the optical vortex topological charge. [ABSTRACT FROM AUTHOR]

The article focuses on the narrative's forming of the fateful return of Odysseus to sea monster Charybdis, focusing on what make him compelled to confront the swallowing eddy. It discusses the importance of a close analysis of Chabrydis and her unique combination of whirlpool, rock and fig tree for exploring her pair with Scylla, and the role of monsters in shaping Odysseus as a distinctive epic hero. It says that Odysseus used his skill to survive against odds and not as a supreme conqueror.

This study presents Computational Fluid Dynamics (CFD) simulation analyses and Particle Image Velocimetry (PIV) experimental research on two-sided (symmetrical) filling of whirlpool separator’s tank and swirling the liquid. This innovative approach enables flow symmetrization and more efficient use of the secondary flow, which causes the hot trub cone formation. The results of the CFD analyses were verified during the experimental research incorporating image anemometry (PIV) and a laboratory scale model. The results were compared to the data obtained from the CFD and PIV performed on a typical model with single-sided filling. The comparison clearly proved the advantage of the two-sided filling in terms of timing and position of the secondary flow, which causes the hot trub cone formation in a whirlpool separator. [ABSTRACT FROM AUTHOR]

We investigated the atmospheric processes and physics that were active during a tsunami-like event hitting Boothbay Harbor area (Maine, USA) on 28 October 2008. The data collected by tide gauges, ground and sounding stations and meteo-ocean buoys in the area were analyzed, together with satellite and radar images. The atmospheric processes were reproduced by the weather research and forecasting model, verified by in situ and remote sensing data. A cold front moved over the area at the time of the event, with embedded convective clouds detected by satellite and radar data and the internal gravity waves (IGWs) detected by radar and reproduced by the model at the rear of the frontal precipitation band. According to the model, the IGWs that passed over Boothbay Harbor generated strong ground air-pressure oscillations reaching 2.5 hPa/3 min. The IGWs were ducted towards the coast without significant dissipation, propagating in a stable near-surface layer capped by an instability at approximately 3.5 km height and satisfying all conditions for their maintenance over larger areas. The intensity, speed and direction of the IGWs were favourable for generation of a meteotsunami wave along the Gulf of Maine shelf. Operational observation systems were not capable of sufficiently capturing the ground disturbance due to a too coarse sampling rate, while the numerical model was found to be a useful tool in eventual future detection and warning systems. [ABSTRACT FROM AUTHOR]

Highlights: [•] We model unsteady flows in a cycling vat using Computational Fluid Dynamics (CFD). [•] We carry out experimental research using Particle Image Velocimetry (PIV). [•] The model and the research lead to comprehending the flow phenomena in a whirlpool. [•] The CFD model, verified with PIV, may turn out to be helpful for designers of such separators. [ABSTRACT FROM AUTHOR]

Intestinal volvulus is a common condition seen in infancy and adulthood, but small bowel volvulus is a rare condition affecting the fetus in utero. Very few cases have been reported describing the ultrasound findings of the same. We present a case report of a case of intestinal volvulus which was diagnosed prenatally based on the ultrasound features of whirlpool sign and coffee bean sign. An emergency caesarian section was performed, small bowel volvulus was confirmed on post-natal ultrasound, and the neonate was subsequently operated. Although these signs have been separately described previously in the literature, in our case both these signs were seen in the same patient. Our case is a rare presentation with the occurrence of volvulus without malrotation, the contrary being more common. [ABSTRACT FROM AUTHOR]

A whirlpool foundation pit is a small-diameter, deep circular pit. Because of its depth and small diameter, a large drawdown is required, and a limited number of wells can be installed inside the pit. During excavation, partially penetrating wells inside and outside the foundation pit have to be installed to lower the water level when the aquifer is too thick. However, partially penetrating wells near partially penetrating curtains cannot be treated by analytical methods. Therefore, it is necessary to use numerical methods to predict dewatering during excavation. Field experiments were performed on whirlpool foundation pit 1880 of Baosteel Group, Shanghai, China, to obtain pumping rates and drawdown, pumping with a single well and two wells in the confined aquifer. The results indicate that the drawdown inside the pit induced by pumping wells outside the foundation pit was small, whereas it was large for pumping wells inside the pit. The pumping wells inside and outside the pit had to be combined to lower the water level. A three-dimensional numerical model was developed to simulate the dewatering process. The hydraulic conductivities of the confined aquifers were inversed by using the pumping tests. Operation schedules were simulated with the corrected model for different combinations of wells inside and outside the pit. The results suggest that different schedules and operation conditions affect drawdown. The monitored results during dewatering indicate that the simulation and field measurements were in agreement. The results can be applied to similar situations. [ABSTRACT FROM AUTHOR]

We report microsphere photonic nanojets, using the Mie theory to analyse the behaviour of the Poynting vector fields for incident visible wavelengths. Optical field structures of optical whirlpools and rhombuses are observed when incident plane waves transmit through 5 μm and 30 μm dielectric microspheres of various refractive indices from n = 1.4 to 2.2 embedded in vacuum and water media. The waist of the photonic nanojets and the distance between the microsphere and the position of maximum electric intensity determines the potential for super-resolution imaging. These parameters vary with the refractive index and size of the dielectric microspheres. We have shown that the waists of the photonic nanojets are beyond the diffraction limit without significant optical diffraction. [ABSTRACT FROM AUTHOR]

The paper presents an application of a dimension similitude theory in an analysis of the flow in a hot trub separator. It presents a procedure for derivation of dimensionless numbers based on a comprehensive analysis of all the forces occurring during fluid flow in a whirlpool. A combination of quotients of elementary forces has allowed to attain the dimensionless numbers. Among them, there are well-known numbers such as the Reynolds and Strouhal numbers, and there is also one original number. Modifications of these numbers have been derived to describe process conditions characteristic for the flow in the whirlpool. Dimensionless numbers relating to the time and the secondary flow parameters occurring at the bottom of the tank have been highlighted. General forms of functions of the dimensionless numbers have been proposed for calculating the time of the whirling motion and the parameters of the flow that form the sediment cone. Practical Applications To this point, designing and assembling whirlpools has not incorporated the knowledge coming from analysis of flows inside the tank occurring during the process of separation. All the information introduced by this publication may contribute to the improvement in designing tanks such as whirlpool. Presented similarity numbers allow for scaling flow phenomena occurring in a cycling vat. [ABSTRACT FROM AUTHOR]

The article presents the discussion on researchers creating whirlpools in materials at the nano and microscale from magnetic spins or electric dipoles. Topics include acting as domain walls and skyrmions showing nanoscale whirls of smoothly evolving spin; and forming exotic polar structures with toroidal-polar topology in a single-layer film of the polymer through self-organized alignment of the polymer chains.

New limitation is introduced -- no body can be accelerated to the mass exceeding the mass of a black hole, in addition to the light velocity limitation. Based on this limitation, new formulae for the theory of relativity and extension of classical equations for mass, length, time can be obtained. Charge relativity has been shown. Formulae for charge and gravitation have been extended. The paper considers the extension of the theory of relativity based on the ether theory development, where crypton (strong wave) functions as a discrete element of super-fluid ether, elementary particles are represented as flat whirlpools, gravitation - as varying density of crypton (strong wave) created by flat whirlpools. The charge is presented as a sinusoid tail stretched by a whirlpool, not coiled and created by a dipole offset of the crypton (ether). The energy of particles is presented in the form of transformation of progressive wave energy into rotational whirlpool energy. It is shown that the gravitation of the black hole has flat form. It is shown that spherical form of stellar explosion with further formation of a black hole transforms into conical one. The equation of gravitation can be written as follows: Fgravitation (ρether density)=[GMm]x[1/(ρether density)²]xP(α, β) INSET: 2. [ABSTRACT FROM AUTHOR]

Quantitative microbiological risk assessment was used to quantify the risk associated with the exposure to Legionella pneumophila in a whirlpool. Conceptually, air bubbles ascend to the surface, intercepting Legionella from the traversed water. At the surface the bubble bursts into dominantly noninhalable jet drops and inhalable film drops. Assuming that film drops carry half of the intercepted Legionella, a total of four (95% interval: 1-9) and 4.5×104 (4.4×104 - 4.7×104) cfu/min were estimated to be aerosolized for concentrations of 1 and 1,000 legionellas per liter, respectively. Using a dose-response model for guinea pigs to represent humans, infection risks for active whirlpool use with 100 cfu/L water for 15 minutes were 0.29 (∼0.11-0.48) for susceptible males and 0.22 (∼0.06-0.42) for susceptible females. A L. pneumophila concentration of ≥1,000 cfu/L water was estimated to nearly always cause an infection (mean: 0.95; 95% interval: 0.9-∼1). Estimated infection risks were time-dependent, ranging from 0.02 (0-0.11) for 1-minute exposures to 0.93 (0.86-0.97) for 2-hour exposures when the L. pneumophila concentration was 100 cfu/L water. Pool water in Dutch bathing establishments should contain <100 cfu Legionella/L water. This study suggests that stricter provisions might be required to assure adequate public health protection. [ABSTRACT FROM AUTHOR]

The off-axis emergence of vortex breakdown (VB) is revealed. The steady axisymmetric flow in a vertical sealed cylinder, which is partially filled with water and the rest is filled with air, is driven by the rotating bottom disk. The numerical simulations show that VB can emerge away from the rotation axis, interface, and walls. As the rotation intensifies, VB first develops in the water region. If the water height is less (larger) than nearly one half of the cylinder radius, VB emerges off (on) the axis. As the rotation further increases, the off-axis VB ring touches the interface and then a thin countercirculation layer develops in the air flow above the water VB domain. This two-fluid VB ring shrinks (it even disappears in a very shallow whirlpool) as the interface approaches the bottom disk. [ABSTRACT FROM AUTHOR]

The Regional Ocean Modeling System (ROMS) is used to systematically investigate equilibrium conditions and seasonal variations of the Benguela system at a resolution of 9 km, including both the large-scale offshore flow regime and the economically and ecologically important coastal upwelling regime. A shelf-edge poleward flow exists in the northern Benguela region (i.e., north of ∼28°S) and is driven primarily by the wind stress curl via the Sverdrup relation. As such, it is strongly seasonal and is most intense during spring and summer, when the wind stress curl is most negative. The poleward flow deepens as it moves southward; between ∼25° and 27°S, much of it veers offshore because of the nature of the wind stress curl and its interaction with the northwestward path of the Benguela Current, which is influenced by alongshore topographical variations. The Benguela Current is driven by nonlinear interactions of passing Agulhas rings and eddies and does not have a striking seasonal signal. In the mean state, it is characterized by two streams. The more inshore stream is topographically controlled and follows the run of the shelf edge. The meandering nature of the offshore stream is a result of the preferential path of Agulhas rings. The model simulates all seven of the major upwelling cells within its domain. The three southernmost cells have the strongest seasonal signal and experience their greatest upwelling during spring and summer months, whereas the two northernmost cells have less seasonal variability but nevertheless have increased upwelling from autumn to spring (and least upwelling in summer), and the central Benguela upwelling cells experience year-round upwelling. The effect of topography on coastal upwelling was investigated by smoothing alongshore coastline and topography variations, which showed that, in all of the seven major upwelling cells, upwelling is enhanced on the downstream side of capes. [ABSTRACT FROM AUTHOR]

Analysis of large-eddy simulation data of the ocean mixed layer under convection reveals that the contribution from wind stress decreases with time as a result of inertial oscillation in the extratropical ocean and that it leads to a rapid increase of the bulk and gradient Richardson number at the mixed layer depth. The criteria for the mixed layer deepening in the widely used mixed layer models, such as the Niiler–Kraus (NK) model, the Price–Weller–Pinkel (PWP) model, and the K-profile parameterization (KPP) model, are examined in view of these results, and its implication on the model predictability is discussed. [ABSTRACT FROM AUTHOR]

The circulation and mesoscale eddies in the Persian Gulf are investigated using results from a high-resolution (∼1 km) Hybrid Coordinate Ocean Model (HYCOM). The circulation in the Persian Gulf is composed of two spatial scales: basin scale and mesoscale. The progression of a cyclonic circulation cell dominates the basin-scale circulation in the eastern half of the gulf (52°–55°E) during March–July. This is primarily the consequence of density-driven outflow–inflow through the Strait of Hormuz and strong stratification. A northwestward-flowing Iranian Coastal Current (ICC; 30–40 cm s−1) between the Strait of Hormuz and north of Qatar (∼52°E) forms the northern flank of the cell. Between July and August the ICC becomes unstable because of the baroclinic instability mechanism by releasing the potential energy stored in the cross-shelf density gradient. As a result, the meanders in the ICC evolve into a series of mesoscale eddies, which is denoted as the Iranian coastal eddies (ICE). The ICE have a diameter of about 115–130 km and extend vertically over most of the water column. Three cyclonic eddies produced by the model during August–September 2005 compared quite well with the Moderate Resolution Imaging Spectroradiometer (MODIS) SST and chlorophyll- a observations. The remnants of ICE are seen until November, after which they dissipate as the winter cooling causes the thermocline to collapse. [ABSTRACT FROM AUTHOR]

The surface circulation of the Caribbean Sea and Gulf of Mexico is studied using 13 years of satellite altimetry data. Variability in the Caribbean Sea is evident over several time scales. At the annual scale, sea surface height (SSH) varies mainly by a seasonal steric effect. Interannually, a longer cycle affects the SSH slope across the current and hence the intensity of the Caribbean Current. This cycle is found to be related to changes in the wind intensity, the wind stress curl, and El Niño–Southern Oscillation. At shorter time scales, eddies and meanders are observed in the Caribbean Current, and their propagation speed is explained by baroclinic instabilities under the combined effect of vertical shear and the β effect. Then the Loop Current (LC) is considered, focusing on the anticyclonic eddies shed by it and the intrusion of the LC into the Gulf of Mexico through time. Twelve of the 21 anticyclonic eddies observed to detach from the LC are shed from July to September, suggesting a seasonality in the timing of these events. Also, a relation is found between the intrusion of the LC into the Gulf of Mexico and the size of the eddies shed from it: larger intrusions trigger smaller eddies. A series of extreme LC intrusions into the Gulf of Mexico, when the LC is observed as far as 92°W, are described. The analyses herein suggest that the frequency of such events has increased in recent years, with only one event occurring in 1993 versus three from 2002 to 2006. Transport through the Straits of Florida appears to decrease during these extreme intrusions. [ABSTRACT FROM AUTHOR]

The natural wonders listed in the folk history known as the Historia Brittonum include Lake Liuan/Lliwan, the site of which is now lost despite featuring in folktales and topographies and containing a dramatic tidal whirlpool/fountain. We identify this key early-medieval wonder as the Whirlyholes, now inactive features near Caerwent, South Wales. [ABSTRACT FROM AUTHOR]

Abstract: The rotating flow field in a cylindrical vessel of a centrifugal-settling vat – the so-called whirlpool – finds the wide application in brewery technology for the separation of solid particles, i.e. hot break. The phenomenon of the conically shaped concentration of sediment reaching the vessel bottom is utilized in this installation. The process of sediment separation in standard whirlpools is carried out with the discharge head H equal to the diameter of a vessel, so the H:D ratio is usually 1. An analysis of the spin-down velocity distribution carried out on the basis of computer simulation results was aimed to establish the effects on liquid clarification and formation of sediment cone. [Copyright &y& Elsevier]

This numerical study reveals stable multi-eddy patterns of a steady axisymmetric air–water flow driven by the rotating bottom disk in a vertical sealed cylindrical container. As rotation strength Re increases, eddies emerge, coalesce, separate, and disappear in both air and water. The topological scenario varies with water volume fraction Hw according to the results obtained for Hw = 0.3, 0.5, and 0.8. Interesting features are: (a) zipper-like chains of air and water eddies forming as the interface bends and (b) bubble-ring air eddies existing in the Re ranges specified in the paper. The stability analysis, performed with the help of a novel efficient technique for two-fluid flows, shows that these multi-eddy motions are stable. The shear-layer instability develops as the interface approaches either the top or bottom of the container and some eddies vanish. The physical reasoning behind the eddy formation and the flow instability is provided. The results are of fundamental interest and can have applications in bioreactors. [ABSTRACT FROM AUTHOR]

In highly viscous electron systems such as high-quality graphene above liquid nitrogen temperature, a linear response to applied electric current becomes essentially nonlocal, which can give rise to a number of new and counterintuitive phenomena including negative nonlocal resistance and current whirlpools. It has also been shown that, although both effects originate from high electron viscosity, a negative voltage drop does not principally require current backflow. In this work, we study the role of geometry on viscous flow and show that confinement effects and relative positions of injector and collector contacts play a pivotal role in the occurrence of whirlpools. Certain geometries may exhibit backflow at arbitrarily small values of the electron viscosity, whereas others require a specific threshold value for whirlpools to emerge. [ABSTRACT FROM AUTHOR]

The article presents photographs of bathtub vortices and whirlpools of water that form in draining containers.

Rates of biogenic silica (bSiO2) production, dissolution, accumulation, and potential bSiO2 export were determined in a Sargasso Sea mode-water eddy (MWE) during two occupations in April 2007. Standing stocks and production rates of bSiO2 within the MWE were 15-20 mmol Si m-2 and 0.8-1.1 mmol Si m-2 d-1, respectively; these values were about six times those reported in April at the nearby Bermuda Atlantic Time-series Study (BATS) site. The MWE also showed positive net bSiO2 production in the upper 140 m (> 0.5 mmol Si m-2 d-1 produced during both occupations), and thus a capacity for bSiO2 accumulation and export. Consistent with previous observations in eddies, the diatom community was dramatically different from that typically observed at the BATS site; diatom abundances were an order of magnitude higher, and larger forms (e.g., Chaetoceros sp.) were prominent. When accounting for both the loss of bSiO2 (between occupations) and the observed positive net bSiO2 production within the MWE, the estimated bSiO2 export rate (1.27 mmol Si m-2 d-1) was twenty times higher than the mean export flux measured at the BATS site with no bloom in progress. If similar processes occur in eddies of other types, then these mesoscale features may be quantitatively important in the regional silica balance, with a strong coupling between increased bSiO2 export and altered diatom community structure. [ABSTRACT FROM AUTHOR]

The article presents science-related news briefs as of November 2003. Researcher Daniel Chiu and colleagues found that fluid circulating in a microscopic whirlpool can reach radial acceleration more than a millon times greater gravity. In other news, it was revealed that two animals can develop very differently even though their genes are identical because of a host of chemicals. Finally, an innovative camera system was created to record life in the deap sea unobtrusively.