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The inlet structures of pipeline pump are characterized by the elbow bend pipe. The inlet structures are susceptible to inlet reflux and uneven impeller inflow, leading to substantial hydraulic losses. This study aims to investigates the flow loss characteristics during the operation of pipeline pump using numerical simulation method. Computational Fluid Dynamics (CFD) was employed to predict the energy characteristics and internal flow patterns. An opening test bench was established to measure the performance parameters of the pipeline pump. A comparison of performance parameters between numerical results and experimental data was conducted to validate the reliability of numerical simulation method. The entropy production theory was also used to qualitatively and quantitatively analyze the magnitude, and identify the specific location of flow loss. A system analysis was made to recognizing the significant impact of suction conditions on the impeller inlet, and the flow state inside the impeller dominates the energy conversion efficiency of the entire pipeline pump. Therefore, the entropy production of the suction and impeller was discussed emphatically, and explore to construct the relationship between the flow loss and the flow field. The results indicate that the energy curve obtained by numerical simulation method was better consistent with the experimental results data. The numerical results data was much little higher than the experimental results ones, but the error between the two was less than 5%, indicating that high credibility of the employed numerical simulation method. The total entropy production of the suction and impeller exhibited a trend of initially decreasing and then increasing with rising flow rate. This behavior was aligned closely with the variation in the main frequency amplitude of pressure fluctuation observed at internal monitoring points. Notably, the total entropy production was smaller in the high-efficiency region and, whereas, the larger in the low-efficiency region, indicating that the entropy production was better represented on the flow loss of the pipeline pump. Furthermore, the variation in total entropy production of the impeller was highly consistent with the suction, indicating that the flow inside the suction affected the flow inside the impeller. The total entropy production of the impeller was outstandingly greater than that of the suction, especially that under biased flow conditions. The total entropy production of the impeller was about 4 four times that of the suction at low flow rate, while the total entropy production of the impeller increased to approximately 15 times that of the suction at high flow rate. The zone of high entropy production rate zone in the suction was primarily distributed in the second bend and outlet, with the increase of flow rate, the entropy production rate showed a trend of first decreasing and then increasing. Notably, the entropy production rate under low flow conditions was hundreds of times higher than that under the rest conditions. The high entropy production rate observed in the suction region, particularly at the second bend and exit positions, can be attributed to the presence of large-scale nucleated vortices during low flow rates and wall-attached vortices during high flow rates. The high entropy production area of the impeller was primarily concentrated at the inlet and outlet. In the radial direction, under low flow rate conditions, the entropy production rate at the outlet was about 7 times higher than that at the inlet under the low flow rate. In the axial direction, the entropy production rate under low flow rate conditions was at least 6 times that under the rest conditions. However, there was no significant variation in the entropy production rate under other flow conditions along the radial and axial direction of the impeller. The high entropy production rate at the low flow rates was primarily caused by the pre-swirl at the impeller inlet and the large-scale stall vortex at the outlet. Conversely, at high flow rates, the high entropy production rate was driven by the severe wall detachment of the fluid and the formation of a strong separation vortex zone at high flow rates. This study finding can offer the valuable insights to identify and optimize the localized flow losses in pipeline pump and enable targeted optimization efforts. [ABSTRACT FROM AUTHOR]

This article investigates the evolution of vortex structures in the impeller channel of a multiphase pump. By capturing the vortices in the impeller channel using the vorticity and Q‐criterion, the generation location of the vortex structures is analyzed, and the pressure fluctuations induced by vortices in the main flow passage of the impeller are studied in terms of their time‐ and frequency‐domain characteristics. The relationship between the vorticity and the amplitude of pressure fluctuations at the main frequency of the impeller is further investigated. This study develops a method of identifying vortices in the impeller channel of the multiphase pump, and reveals the intrinsic connection between the vortices and pressure fluctuations in the main flow passage. These findings offer some suggestions for eliminating the influence of vortices and enhancing the pressurizing capabilities of multiphase pumps. [ABSTRACT FROM AUTHOR]

Measuring and controlling flow in conduits is one of the most important issues in the management and operation of irrigation and drainage systems. Investigations on this issue are of great importance for cost-effectiveness and ease of operation, construction, as well as increasing the accuracy of flow measurement and control. In this research, the hydraulic parameters of the flow on multiple elliptic lopac gates in submerged flow conditions have been investigated. This study was done using Flow3D fluid dynamics simulation software. The simulations are performed in three flow rates 20, 40, and 60 liters per second, three opening rates 30, 45, and 60 degrees and three absorption rates 70, 80, and 90 percent. The maximum flow velocity, discharge coefficient and flow vortices are investigated, and their analysis is described. Regarding the maximum velocity, the results showed that when using lopac elliptic gates in submerged conditions compared to free flow conditions, the maximum velocity in the flow rates (20, 40 and 60) liters per second in the opening of 30 degrees on average for the amount of absorption (70, 80, and 90) percent will decrease by 9, 30, and 54 percent, respectively, at 45-degree opening, by 8, 22, and 38 percent, and at 60-degree opening, by 12, 22, and 44 percent, respectively. The results regarding the Discharge coefficient showed that when multiple lopac elliptic gates are used in submerged conditions compared to free flow conditions, the Discharge coefficient in the flow rates of (20, 40, and 60) liters per second in the opening of 30 degrees on average For the extraction rate (70, 80 and 90) percent, 8, 26 and 45%, respectively, at 45 degree opening, 16, 34 and 49%, respectively, and at 60 degree opening, 17, 36 and 54%, respectively will find Finally, the observations showed that when multiple elliptic lopac gates are used in free flow conditions, high-strength vortices are formed compared to multiple elliptic lopac gates in submerged flow conditions. However by examining the flow pattern of multiple elliptic lopac gates in submerged flow conditions, the size of the eddies has decreased, and as a result, its strength has decreased. [ABSTRACT FROM AUTHOR]

Agrivoltaics is a relatively new term used originally for integrating photovoltaic (PV) systems into the agricultural landscape and expanded to applications such as animal farms, greenhouses, and recreational parks. The dual use of land offers multiple solutions for the renewable energy sector worldwide, provided it can be implemented without negatively impacting agricultural production. However, agrivoltaics represent a relatively new technology, facing challenges including economic viability, vulnerability to wind loads, and interference with growing crops. This paper reviews the recent research on integrating agrivoltaics with farming applications, focusing on challenges, wind impact on agrivoltaics, and economic solutions. The effect of agrivoltaics on temperature control of the lands is a critical factor in managing (1) water and the soil of the land, (2) animal comfort, and (3) greenhouse productivity, positively or negatively. In this review, a contradiction between the different versions of the American Society of Civil Engineers (ASCE) standards and the wind tunnel results is shown. Important factors affecting the wind load, such as damping and mass increase, optimum stow position, and aerodynamic edge modification, are highlighted with emphasis on the significant knowledge gap in the wind load mitigation methods. [ABSTRACT FROM AUTHOR]

Recovery of endangered species is challenging and lengthy, especially when it involves reintroduction and dynamic environmental conditions. Because managers often need to decide between many management strategies with uncertain outcomes, periodically assessing progress toward recovery using population viability analysis (PVA) can help guide decision‐making. We developed a PVA for the critically endangered Puerto Rican parrot (Amazona vittata) to evaluate current status and potential future management strategies to reach goals set in the Recovery Plan. Having grown from their nadir of 13 birds in 1976 to 686 in 2021, the recovery effort has made great progress. Using 15 years of data, we built an individual‐based PVA that included interactions between two captive and three wild populations connected via annual releases. If management continues as planned, the wild populations have no to moderate risks of extinction (0–32%) over the next 100 years. However, wild populations remain dependent on releases to sustain growth, and recovery targets for stable population growth and connectivity have not yet been reached. Our analysis suggests that hurricanes are an impediment to reaching recovery targets and impact some wild populations more than others based on geography. Projections with climate‐change‐induced higher hurricane impact resulted in wild populations being less likely to stabilize. We identified demographic rates and associated management strategies that could positively impact wild populations: increasing reproduction (e.g., via increasing artificial nests, improving nest success) and decreasing first‐year mortality (e.g., via targeted predator control). Based on our current understanding of Puerto Rican parrot demographics, species recovery will continue to be management‐dependent unless demographic rates can be altered. As more data are gathered, especially for data‐sparse populations and in the face of environmental change, future iterations of this model can re‐evaluate progress, update management strategies, and provide support for deciding if and when to delist this iconic species. [ABSTRACT FROM AUTHOR]

The problem of two-dimensional flow of a viscous weakly compressible fluid in a square cell under excitation by a spatially periodic static external force (Kolmogorov flow) is considered. A new method for determining the flow structure is presented. It is based on the analysis of the vorticity field at different times. This method is used to classify types of flows the characteristics of which were obtained by numerical simulation. The main flow regimes are identified depending on the values of the friction coefficient against the bottom and the pumping force: laminar, chaotic and vortex regimes. Transitional types of flow are studied separately: the quasi-periodic regime, which arises through a sequence of bifurcations when the laminar and chaotic flow regimes change, and the alternation regime, which occurs during the transition from the chaotic to vortex flow. Phase diagrams are constructed in the space the amplitude of the external force–the friction coefficient against the bottom, which made it possible to classify the type of flow on the basis of the values of the friction coefficient against the bottom and the pumping force. [ABSTRACT FROM AUTHOR]

The jet impingement flash technology represents a paramount research subject in the domain of heat and mass transfer. To augment its commercial potential, the conjunction of annular multi‐aperture jet impingement with negative pressure flash evaporation is introduced in this study. The employment of an annular nozzle array is integral to the enhancement of the heat and mass transfer efficiency between the phases. The Realizable k‐ε model is used in this study. The negative pressure flash vaporization model was also developed by introducing a mass source term and an energy source term based on the Mixture model. The flow characteristics are characterized using numerical simulation. Additionally, the λ2 vortex identification criterion is investigated the vortex structure. The simulation results exhibit good agreement with experimental findings, demonstrating that a higher initial vacuum leads to a stronger flashing effect and a more chaotic movement of the flow group within the flow field. Thus, this study provides a reference method for the structural design and optimization of annular symmetric jet impingement negative pressure deammonia chemical equipment for engineering applications. [ABSTRACT FROM AUTHOR]

In this study, a disk-type bluff body was installed at the upper part of a nozzle exit, and the circular jet inside the nozzle was controlled using a dielectric barrier discharge (DBD) plasma actuator (DBD-PA). The effects of the changes in the excitation frequency of the jet induced by the DBD-PA on the jet diffusion were elucidated. The experiments included visualization of the jet cross-section, particle image velocimetry analysis, and velocity measurements using an I-type hot-wire anemometer. When the DBD-PA was driven at a specific burst frequency (900–1400 Hz), a lock-in phenomenon occurred, in which the frequency of vortices generated in the initial jet coincided with the burst frequency. This lock-in phenomenon suppressed the merging of vortices by generating vortices at regular intervals. When vortex merging was suppressed, the jet was less likely to be entrained into the recirculation flow generated by the bluff body, thereby increasing the downstream jet width and average flow rate. [ABSTRACT FROM AUTHOR]

The intricate flow dynamics within a vortex settling basin (VSB) make it challenging to establish a generalized regression model for accurately estimating sediment removal efficiency. Therefore, this study proposes an alternative approach using the Adaptive Neuro Fuzzy Inference System (ANFIS) to predict the sediment removal efficiency of VSB. The model is developed based on a comprehensive and reliable database sourced from literature, encompassing a wide range of hydraulic and geometrical variables from laboratory and field studies. The sediment removal efficiency of the VSB is modelled as a function of five key variables: water abstraction ratio, depth ratio, width ratio, diameter ratio, and particle Reynolds number. Training and testing data are extracted from laboratory and field datasets in various reputable references. Numerical tests reveal that ANFIS yields more accurate VSB removal efficiency predictions than previous empirical approaches. Sensitivity analysis further indicates that the particle Reynolds number exerts a more significant influence on sediment removal efficiency than the other independent parameters. This ANFIS-based approach offers an enhanced understanding and prediction capability for the complex processes occurring within a VSB. [ABSTRACT FROM AUTHOR]

【Objective】 This paper is to investigate how changes in flow pattern at the water inlet influence the measurement accuracy of box-type integrated measurement and control gates and water flow in front of the gate. 【Method】 Using a commonly used 600 mm × 600 mm flow measurement box in irrigation systems as the test subject, 98 model tests were conducted at an indoor testing facility. Disturbance facilities were set up to study the effects of flow symmetry, gate opening, and water level changes on the flow pattern and measurement accuracy in front of the gate. 【Result】 ① The intensity, frequency, and duration of vortices in the flow measurement box vary across different operating conditions. When the measurement box is non-submerged, surface depression vortices are predominant, with minimal impact on measurement accuracy. When the box is submerged and water depth exceeds 20 cm, vortex intensity decreases with increased submergence, but when the depth is less than 20 cm, vortex intensity reaches a maximum, and through-vortices form, causing a significant increase in measurement error. ② The symmetry of the inlet flow pattern is a primary factor influencing vortex formation. Under asymmetric inlet flow conditions, suction vortices are likely to occur in the measurement box, significantly increasing measurement error, with a maximum error of about 22.58%. 【Conclusion】 Adjusting submergence depth, gate opening, and inlet flow symmetry effectively reduces vortex intensity around the measurement box and improves measurement accuracy.

Abstract This paper presents a novel method to continuously control the initial separation distance d between two plasma vortices of electrons. In this method, the two electron columns are initially confined individually in two coaxial Malmberg–Penning traps with different axial lengths. They rotate around the trap axis at different rotation frequencies due to the $$\varvec{E}\times \varvec{B}$$ drift. Their different rotation rates cause periodic changes in their relative azimuthal positions. The initial conditions are established when the two columns are stretched along magnetic field lines of a unified Malmberg–Penning trap. This method precisely provides a simple and continuous adjustment of the initial d and facilitates efficient investigation of the interaction of the two plasma electron vortices.

Abstract This article investigates the evolution of vortex structures in the impeller channel of a multiphase pump. By capturing the vortices in the impeller channel using the vorticity and Q‐criterion, the generation location of the vortex structures is analyzed, and the pressure fluctuations induced by vortices in the main flow passage of the impeller are studied in terms of their time‐ and frequency‐domain characteristics. The relationship between the vorticity and the amplitude of pressure fluctuations at the main frequency of the impeller is further investigated. This study develops a method of identifying vortices in the impeller channel of the multiphase pump, and reveals the intrinsic connection between the vortices and pressure fluctuations in the main flow passage. These findings offer some suggestions for eliminating the influence of vortices and enhancing the pressurizing capabilities of multiphase pumps.

The evolution of unforced and weakly damped two-dimensional turbulence over random rough topography presents two extreme states. If the initial kinetic energy [Formula: see text] is sufficiently high, then the topography is a weak perturbation, and evolution is determined by the spontaneous formation and mutual interaction of coherent axisymmetric vortices. High-energy vortices roam throughout the domain and mix the background potential vorticity (PV) to homogeneity, i.e., in the region between vortices, which is most of the domain, the relative vorticity largely cancels the topographic PV. If [Formula: see text] is low, then vortices still form but they soon become locked to topographic features: Anticyclones sit above topographic depressions and cyclones above elevated regions. In the low-energy case, with topographically locked vortices, the background PV retains some spatial variation. We develop a unified framework of topographic turbulence spanning these two extreme states of low and high energy. A main organizing concept is that PV homogenization demands a particular kinetic energy level [Formula: see text]. [Formula: see text] is the separator between high-energy evolution and low-energy evolution.

The vortex distribution in rotating Bose-Einstein condensates (BEC) trapped in a potential composed of two-dimensional optical lattice and harmonic potential is studied by using the multigrid preconditioned conjugate gradient method, and the effects of the depth of the optical lattice, the lattice constant and the rotation frequency of the condensates on the vortex distribution in rotating condensates are discussed. The results show that due to the introduction of the optical lattices, vortices are generated in the condensates, and the vortices are located with the minimum value of the external potential. As the depth of the optical lattice increases, the condensates gather at the bottom of the optical lattice, forming a lattice-like distribution, in which the vortices form vortex pairs and merge to form larger vortices. When the lattice constant is small, the vortex distribution in BEC is similar to the Abrikosov vortex lattice. With the increase of the lattice constant, the distribution of vortices in the condensate becomes diversified, and a three-layer structure appears. When the rotation frequency of the condensates increases, the number of vortices in BEC increases, and the vortex distribution becomes more complex and varied. The density distribution range of the condensate also expands with the increase of the rotation frequency. When the rotation frequency of the condensate is close to the frequency of the harmonic potential, that is, when the condensate is at the lowest Landau level approximation, the number of vortices in the condensate increases dramatically, and the phenomenon of vortex combination and fusion appear, then a vortex pattern will be formed. [ABSTRACT FROM AUTHOR]

Microvortices are emerging components that impart functionality to microchannels by exploiting inertia effects such as high shear stress, effective fluid diffusion, and large pressure loss. Exploring the dynamic generation of vortices further expands the scope of microfluidic applications, including cell stimulation, fluid mixing, and transport. Despite the crucial role of vortices' development within sub-millisecond timescales, previous studies in microfluidics did not explore the modulation of the Reynolds number (Re) in the range of several hundred. In this study, we modulated high-speed flows (54 < Re < 456) within sub-millisecond timescales using a piezo-driven on-chip membrane pump. By applying this method to microchannels with asymmetric geometries, we successfully controlled the spatiotemporal development of vortices, adjusting their behavior in response to oscillatory flow directions. These different vortices induced different pressure losses, imparting the microchannels with direction-dependent flow resistance, mimicking a diode-like behavior. Through precise control of vortex development, we managed to regulate this direction-dependent resistance, enabling the rectification of oscillatory flow resembling a diode and the ability to switch its rectification direction. This component facilitated bidirectional flow control without the need for mechanical valves. Moreover, we demonstrated its application in microfluidic cell pipetting, enabling the isolation of single cells. Consequently, based on modulating high-speed flow, our approach offers precise control over the spatiotemporal development of vortices in microstructures, thereby introducing innovative microfluidic functionalities. [ABSTRACT FROM AUTHOR]

Where stable source populations of at-risk species exist, translocation may be a reasonable strategy for re-establishing extirpated populations. However, the success rates of such efforts are mixed, necessitating thorough preliminary investigation. Stochastic population modeling can be a useful method of assessing the potential success of translocations. Here, we report on the results of modeling translocation success for the Gallinula galeata sandvicensis or 'alae 'ula (Hawaiian Common Gallinule), an endangered waterbird endemic to the Hawaiian Islands. Using updated vital rates, we constructed a model simulating 3 existing extant (wild) source populations and a hypothetical recipient site on another island. We then projected the effects of 6 different translocation scenarios and sensitivity of the results to variation of three important demographic parameters on the probability of extinction (PE) of the reintroduced and donor populations. Larger translocations, of at least 30 birds, had low probability of extinction in the reintroduced population, but raised extinction risk of the smallest source population. Spacing out translocations in time (e.g. 10 birds translocated in total in 3 installments over 9 years), led to lower PE than translocating all individuals at once (i.e. bulk translocations) for both the source and reintroduced populations. Brood size and hatch-year juvenile survival had a disproportionate impact on reintroduced population viability. Importantly, the reported juvenile survival rate is very near the threshold for population failure. This suggests that post-introduction and subsequent management of wetlands, particularly predator control, could be critical to reintroduction success. We recommend that individuals should be translocated from multiple, genetically distinct subpopulations to reduce the possibility of inbreeding depression. Based on this analysis, the recipient wetland should be sufficiently large that it can support at least 25 pairs of gallinules. Based on recent estimates of population densities on O'ahu, such a wetland would need to be between 3.75 and 74.6 ha. [ABSTRACT FROM AUTHOR]

The flow field structure within the clearances of turbomachinery is complex and diverse, exhibiting high-dimensional nonlinearity. How to accurately extract the main structures that affect the internal flow within the turbine from the complex clearance flow has always been a key issue. To explore the impact of the dynamic structure of the clearance flow on the mainstream region in a centrifugal pump, this study combines the dynamic mode decomposition (DMD) method to conduct a thorough analysis of the velocity and pressure pulsation frequencies in the multi-physics fields within the clearance. The study has identified the main characteristic structures under different physical conditions in the clearance and has established the relationship between the characteristic structure frequencies in different physical fields and the impeller frequency. The research indicates that the internal flow within the clearance affects the occurrence of vortices in the volute. Under design conditions, the velocity field within the clearance is primarily influenced by high-order harmonic frequencies of the impeller, and the pressure field is mainly affected by low-order harmonic frequencies of the impeller. This reflects the crucial influence of impeller frequency and inlet flow on the coherent structures within the clearance flow. The research results offer new insights and methods for analyzing complex internal flows in large turbomachinery. [ABSTRACT FROM AUTHOR]

To investigate the gas-liquid two-phase flow characteristics in an emergency rescue drainage pump, the MUSIG model was adopted to analyze the effect of the gas phase on the internal flow characteristics of the pump. The results show that the gas phase predominantly accumulated in the impeller region, with significant tendencies for large diameter bubbles to fragment into smaller diameter bubbles. The bubbles of the impeller blades converged towards the middle zone of the blade near the hub, forming an air pocket that obstructed the flow passage through the impeller. Such findings ultimately resulted in a loss of pump performance. Moreover, as the diameter of inlet bubble increased, there was a greater tendency for the gas phase to converge into a concentration distribution, leading to unfavorable flow conditions in the pump. This phenomenon ultimately led to a decline in pump performance and may have resulted in the loss of water conveyance functionality. Meanwhile, the O method was used to investigate the vortex flow within the drainage pump under different gas contents. As the inlet gas volume fraction increased, the vortex area expanded and the vortex tended to fragment into multiple smaller pieces, resulting in the formation of more complex structures. [ABSTRACT FROM AUTHOR]

A differential equation of motion is proposed for vortex development. By that means, the limits of existence of vortex flows may be established, and the vorticity field may be determined. [ABSTRACT FROM AUTHOR]

To improve estimation of sea salt deposition distributions on structural surfaces such as that of an airborne sea salt and corrosion sensor, we numerically simulated approaching flows with particles around a vertical flat plate. This is a typical object that mimics a sensor with a support plate. We used a computational fluid dynamics (CFD) model based on the unsteady Reynolds averaged Navier-Stokes equation. After validating the results by comparison with existing studies for flows with particles around a cylinder, we examined the changes in particle impaction efficiency on the plate with different approaching flow directions (0, 45 deg) and particle diameters (5 © 10-6-1.6 © 10-4 m). The impaction efficiency increases rapidly with particle diameter, whereas the influence of flow direction is small. Such increases in impaction efficiency are due to contributions from inertial impaction, and thus the variation in Stokes number with wind speed and the plate size can be used to predict the flow and particle conditions required for increases in impaction efficiency. The efficiencies for small particles on the front surface of the plate are higher than those on a cylinder. The impactions of small particles on the plate are locally activated by flow separations around a bluff body, whereas those on a cylinder are caused by intercepts without flow separations. [ABSTRACT FROM AUTHOR]

The interfaces between superconductors and other materials have long been established as being an important part in the exploration of new physics to aid in our understanding of superconductivity and open us up to new technological advancements. Herein this article we analyse the recent progress made in the understanding of superconductivity at the interfaces involving a wide range of functional materials, mostly looking at two-dimensional (2D) systems. We start off in the first half of this review by focusing on magnetic and superconductive hybrid heterostructures, as well as the resulting physical phenomena from these systems. The first is a section on vortex and anti-vortex phenomena; the second key area is ferromagnet–superconductor hybrid phenomena with particular interest of magnetic skyrmions, the third is the novel frontier based on 2D magnetic and superconductive interfaces particularly examining Ising superconductivity at these interfaces; the fourth is superconductivity at anti-ferromagnetic interfaces and finally half-metals at superconducting interfaces. The second half of this review focuses on superconductivity at insulating and other functional interfaces. Examining firstly, Mott insulator interfaces with wide ranging discussions about how such interfaces can enhance our understanding in high-temperature superconductive cuprates and other unconventional superconductor systems such as the nickelates; in the second section the interface of 2D and 3D ferroelectric materials with superconductors with a key emphasis on devices that have been developed to control the superconducting phase; Topological insulators at interfaces with superconductors is the third section; and lastly 2D twisted material interfaces are explored, including the newly discovered magic angle interfaces discovered with graphene and other van Der Waals materials. It is anticipated that this review will lead to further interest in such interfaces to improve our understanding and expose the exotic science behind these interfaces. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, we present a numerical investigation into the influence of electric and magnetic fields on the dynamics of a suspended liquid film that carries an electric current. A nonuniform magnetic field is considered utilizing a disk-shaped magnet located above the two-dimensional fluid. Electric and magnetic forces exerted on the fluid induce a new dynamical features. We perform a numerical study of the dynamics of such two-dimensional fluid system commonly named Liquid Film Motor. The presence of the nonuniform external magnetic field causes changes in the fluid’s behavior. Specifically, the previously symmetric vortex becomes asymmetric under the influence of the magnetic field. In this dynamic behavior, as the external magnetic field increases, the center of the vortex shifts in a direction perpendicular to the electric current passing through the fluid film. The unique combination of electric and magnetic field allows to manipulate the motion of the vortex without resorting to traditional mechanical methods. This finding implies that the motion of the vortex can be directed and controlled by adjusting the strength of the external magnetic field, without the need for direct contact with the fluid or mechanical tools. [ABSTRACT FROM AUTHOR]

The engineering of ferroic orders, which involves the evolution of atomic structure and local ferroic configuration in the development of next‐generation electronic devices. Until now, diverse polarization structures and topological domains are obtained in ferroelectric thin films or heterostructures, and the polarization switching and subsequent domain nucleation are found to be more conducive to building energy‐efficient and multifunctional polarization structures. In this work, a continuous and periodic strain in a flexible freestanding BaTiO3 membrane to achieve a zigzag morphology is introduced. The polar head/tail boundaries and vortex/anti‐vortex domains are constructed by a compressive strain as low as ≈0.5%, which is extremely lower than that used in epitaxial rigid ferroelectrics. Overall, this study c efficient polarization structures, which is of both theoretical value and practical significance for the development of next‐generation flexible multifunctional devices. [ABSTRACT FROM AUTHOR]

In this paper, we study the ground state of two-component spin–orbit-coupled (SOC) Bose–Einstein condensates with mass imbalance. Our results are based on the framework of mean-field Gross–Pitaevskii theory. The effects of unequal atomic mass and SOC strength are studied. Different density structures such as heliciform stripes, linear stripes and string vortex chains are found. Different density structures such as heliciform stripes, linear stripes and string vortex chains are found. With the increase of SOC strength, the azimuthal phase separation is kept while radial phase separation is broken. In addition, increasing the mass ratio is unfavorable to vortex formation, whereas more vortices can be generated by increasing the SOC strength. We also discuss the physical quantities such as angular momentum per atom and spin polarisation, for a larger mass ratio, showing that angular momentum gets a little bigger as the SOC strength increases and the first-order phase transition does not exist. [ABSTRACT FROM AUTHOR]

In this paper, symmetric Pearcey Gaussian beams (SPGBs) are studied in a Kerr medium. By varying the initial input power, the autofocusing ability of the beams is investigated, to find a clear restrictive relationship between the breath‐like structure and the initial input power. The critical collapse power is investigated when SPGBs change from discrete beams to regular breath‐like structure. Finally, the transmission of SPGBs is discussed under different phase modulation when SPGBs are affected by astigmatic, the whole beam is rotated and the angle of rotation can be controlled. [ABSTRACT FROM AUTHOR]

This study employed computational fluid dynamics-discrete phase model (CFD-DPM) to investigate the transport characteristics of transient high-temperature dust in a vertical tee duct. Utilizing the large eddy simulation (LES) model, the research elucidated the flow characteristics, temperature field distribution, and particle deposition patterns within the tee duct. Specifically, it was observed that the vortex generated by the tee duct dissipated when x/D exceeds 20. Furthermore, high-temperature fluid exhibited an upward migration within the pipe by buoyancy, concurrently intensifying flow velocity fluctuations. Particle diffusion was initially driven by particle inertia and later became dominated by the combined effects of vortex and buoyancy. The deposition of particles displayed a trend of a sharp increase and decrease, then a gradual increase and decrease along the duct. The particle deposition can be divided into three stages, each governed by varying influencing factors on particle movement: (a) particle inertia within the range 0 < x/D < 5; (b) vortex carry spanning 5 < x/D < 20; and (c) turbulent pulsations beyond 20 < x/D. The total deposition mass was decreased by 50% by the vortex. This article provides a comprehensive description of the diffusion and deposition of transient high-temperature dust in a tee duct. [ABSTRACT FROM AUTHOR]

In order to determine the most suitable turbulence model for studying the aerodynamic performance of bus, the effects of different turbulence models on the aerodynamic characteristics of bus were investigated. A comparative analysis was conducted on five turbulence models (IDDES, DDES, DES, LES, URANS). The pressure distribution on the cross section at x=0 and y=0 is also analyzed for each model. The results reveal that IDDES accurately captures the negative pressure at the rear of the bus and predicts the pressure gradients more effectively than other models. IDDES also captures more vortices at the head of the bus and predicts the wake flow more widely than other models. DDES has obvious shedding phenomenon in the wake flow, while IDDES provides a relatively smooth airflow trajectory, but its prediction of airflow trajectory at a distance is less clear. Through quantitative and qualitative analyses of the aerodynamic characteristics of bus under different turbulence models, it can be concluded that IDDES is the most suitable turbulence model to study the aerodynamic characteristics of bus. [ABSTRACT FROM AUTHOR]

Previous studies have introduced a resonant caisson designed to enhance wave energy extraction in regions with low wave energy density; however, its operational mechanism remains poorly understood. This paper seeks to elucidate the operational mechanism of the resonant caisson by leveraging Star-CCM+ for Computational Fluid Dynamics (CFD) simulations, focusing on the influence of guides and their dimensions on the water levels, flow velocities, and vortex dynamics. The findings demonstrate the remarkable wave-amplification capabilities of the resonant caisson, with the maximum amplification factor reaching 2.31 at the calculated frequency in the absence of guides. Incorporating guides and expanding their radii substantially elevate the flow rates, accelerate the water currents, and alter the vortex patterns, thereby further enhancing the amplification factor. This study will provide a reference for optimizing the design of resonant caissons and wave energy converters based on resonant caissons, thus promoting the effective use of wave energy resources. [ABSTRACT FROM AUTHOR]

Background and Objectives: Today, due to the reduction of water resources and the issue of excessive water consumption in the agricultural sector, for the purpose of distribution, delivery, and flow regulation to waterways, and to prevent water losses, novel structures with better efficiency and easier operation have been introduced by researchers. Lopac gates are one of the hydraulic structures for flow control and regulation, which have features such as the possibility of automation, open-channel flow, and easier installation and placement compared to other structures. In this study, a rectangular multi-lopac gate, which is one of the novel types of lopac gates, has been used. Considering the easier operation of smaller gates compared to larger gates, in this study, has been investigated the effect of two smaller gates instead of a single gate on the hydraulic characteristics in the submerged condition with 70%, 80%, and 90% submergence levels and with the aim of increasing efficiency and ease in design and construction. Materials and Methods: In the present study, several simulations were performed to validate and select the turbulence model. After investigation the performed simulations, a mesh of 800,000 cells, the RNG turbulence model, and a time of 40 seconds for the flow to reach stability were selected. Then, to investigate the hydraulic parameters of maximum shear stress, maximum horizontal force acting on the gate, velocity distribution range, and shear stress in the rectangular lopac gate under submerged flow conditions, and compare it with the single gate case, simulations were performed at three discharges of 25, 35, and 45 liters per second, opening angles of 35, 40, and 45 degrees, and three submergence levels of 70%, 80%, and 90% in two different geometries, with a total of 54 simulations. Results: The results showed that the maximum shear stress has an inverse relationship with submergence and opening angle, and the maximum horizontal force acting on the gate has a direct relationship with submergence and discharge. It was observed that all the investigated parameters in the two-gate case decreased compared to the single-gate case, and the amount of this decrease in the horizontal force acting on the gate was 33.5%, which was the highest decrease at a discharge of 25 liters per second, an opening angle of 45 degrees, and 90% submergence, and the lowest decrease was at a discharge of 25 liters per second, an opening angle of 45 degrees, and 70% submergence. The reduction in the maximum shear stress in the two-gate case compared to the single-gate case was 13.25%, with the highest decrease of 23.29% occurring at a discharge of 45 liters per second, an opening angle of 45 degrees, and 90% submergence, and the lowest decrease of 6.21% occurring at a discharge of 45 liters per second, an opening angle of 35 degrees, and 80% submergence. It was also observed that the distribution range and elongation of velocity and shear stress on the flume bed increased with increasing discharge and opening angle, and in general, the distribution range and elongation of velocity and shear stress on the flume bed decreased in the two-gate case compared to the single-gate case. Conclusion: According to the results, it can be stated that the distribution range of velocity and shear stress has a direct relationship with discharge and opening angle, and the elongation of the velocity and shear stress distribution in the two-gate case decreased compared to the single-gate case. The maximum shear stress has an inverse relationship with the opening angle and submergence, and it decreases by 13.26% compared to the single-gate case. This is due to the reduction of the area of vortices in the two-gate case. Investigating the maximum horizontal force acting on the gate showed that this parameter has a direct relationship with flow rate, opening angle, and submergence, and it decreases by 33.5% in the multigate cases compared to the single-gate case. [ABSTRACT FROM AUTHOR]

Floating offshore wind turbines (FOWTs) exhibit complex motion with multiple degrees of freedom due to the interaction of wind and waves. The aerodynamic performance and wake characteristics of these turbines are highly intricate and challenging to accurately capture. In this study, dynamic fluid body interaction (DFBI) and overset grid technology are employed to investigate the dynamic motion of a 5 MW FOWT. We use the volume of fluid (VOF) method and improved delayed detached eddy simulation (IDDES) model to investigate the aerodynamic performance and wake evolution mechanism for various wave periods and heights. According to the findings, the magnitude of the pitch motion increases with the period and height of the waves, leading to a decrease in both the power output and thrust; the maximum power was reduced by nearly 6.8% compared to a wind turbine without motion. The value of power and thrust reduction varies for different wave periods and heights, and is influenced by the relative speed and pitch angle, which play a crucial role. Wind–wave coupling has a significant impact on the evolution of both wake and vortex structures for FOWT. The wake shape downstream is also dynamically influenced by the waves. In the presence of wind and wave coupling, the interaction between the wind turbine and the wake is heightened, leading to the merger of two unstable vortex rings into a single, larger vortex ring. The research unveils a comprehensive picture of the offshore wind energy dynamics and wake field, which holds immense significance for the design of floating wind turbines and the optimization of wind farm layout. [ABSTRACT FROM AUTHOR]

Hydrogen ejectors effectively utilize excess unreacted hydrogen. However, traditional ejectors have limited operational ranges and are only suitable for specific power ranges. This paper presents a dual-nozzle ejector aimed at broadening its operational range through different working modes. A simulation model, validated by experiments, is employed based on the working principles of ejectors. Spiral blades are installed at drive end to improve the recirculation efficiency. Flow characteristics, including streamwise and spanwise vortices at high power, are also investigated in different modes. Results indicate that optimal operating range for Ring-nozzle(RN) mode is between 31.1 and 124.4A. When output current exceeds 124.4A, it is necessary to switch to Central-nozzle (CN) or Double-nozzles (DNs) mode. Analysis of streamlines and velocity vectors reveals that installing spiral blades can modify directions of primary flow. Blades with appropriate distortion should be selected. In CN mode, when stack reaches 60% of rated power, installing 20° spiral blades has a minimal impact on stability of radial flow. Installing 30° or 40° spiral blades is suitable for full-load condition. In DNs mode, installing 30° spiral blades enhances acceleration of gas flow with lower influence from radial influx. This ejector provides assurance for upgrade of fuel cell stacks by incorporating recirculation technology. • A dual-nozzle ejector with spiral guide blades is designed, verified and evaluated. • Installed spiral blades change direction and gather kinetic energy of primary flow. • Advantageous working conditions of different modes with blades are discussed. • Flow mechanism of different blades under high power in two modes is analyzed. • Flow acceleration and losses should be balanced by changing the twist of blades. [ABSTRACT FROM AUTHOR]

Optical elements based on nanomaterials are becoming major avenues to satisfy the technological requirements of compact, lightweight, and tunable elements of the emerging terahertz (THz) field. A new generation of diffractive components integrating specific geometry with additional features (flexibility, stretchability, rotation, and other approaches for tuning properties) extends the functionality of wavefront control. Here, an innovative approach is demonstrated to control the THz wavefront via a layered composition of spiral zone plates (SZPs) with tunable mutual orientation and scaling. As a proof of concept, the SZP is designed using Laguerre‐Gauss mode analysis with further fabrication and experimental characterization of the resultant vortex beams. For each single SZP, a flexible element is proposed based on a thin film of single‐walled carbon nanotubes deposited on a stretchable substrate. Thus, this diffraction element can be tuned not only by rotation (along the azimuthal direction), but also by its stretching (in the radial direction). The spatial tuning of the developed SZPs (spiral zone plates) opens up an efficient, convenient, and highly customizable approach for the manipulation of vortex beams. [ABSTRACT FROM AUTHOR]

AbstractThe current work is devoted to a comparative analysis of enhanced co-factors in solidified floating organic drop microextraction methods (SFODME) and an environmental assessment. Also, the description of SFODME, with a focus on its applications in the determination of metals in different matrices, was explained. The impact of several parameters, developments, and greenness evaluations was introduced. Especially, the review provides a concise overview of the multiple approaches to SFODME, with an emphasis on environmentally friendly, supported co-factors. These mods include ultrasound, vortex, and air-assisted SFODME procedures. The selectivity and sensitivity increase when co-factors are added to SFODME. Lastly, the analysis also aims to select tools (Analytic GREEnness Metric Approach (AGREE), Red-Green-Blue (RGB12), and Blue Applicability Grade Index (BAGI)) that have been described as environmentally friendly. Additionally provide an explanation of the data collected, compare, and emphasize the advantages of certain characteristics in each tool. Furthermore, case studies and comparisons for three tools were shown. [ABSTRACT FROM AUTHOR]

Leaf vein drip irrigation emitter is a new type of drip irrigation emitter. The flow channel achieves energy dissipation through flow diversion, turning, and sudden contraction. In this study, three design schemes (B1, B2, and B3) were proposed by optimizing the flow channel structure to improve the hydraulic performance, and the feasibility of the schemes was verified by combining them with experiments. The results show that the flow index of the three structural optimization designs were 0.52, 0.51, and 0.50, with errors of less than 5% compared to the measured results. Compared to the original structure A1 (with a flow index of 0.53), the hydraulic performance was improved by 0.4%, 3.2%, and 5.7%. Compared with A1 and B1, the turbulence kinetic energy of the main flow region of the B2 and B3 structures was significantly increased, and the proportion of low turbulence kinetic energy area had decreased. The increase in turbulent kinetic energy drove the liquid to remain turbulent, increasing the ability of particulate matter to flow out of the flow channel. The irregular changes in the velocity field in the high-speed zone result in a large velocity gradient, which maximizes the turbulent kinetic energy and entropy generation in the area. Among the four flow channel structures, the region with the highest turbulence dissipation was located in the upper part of the internal structure of the flow channel. There were apparent vortex regions in flow channels A1, B1, and B3 for energy dissipation, with energy dissipation coefficients being 6.07–8.51. However, the average flow velocity in this region was only about 0.2 m/s, and particulate matter was easily trapped. When the particle diameter increased, compared with the other three design structures, B2 had the best particle passage ability. Combined with the muddy water experiment, the optimized flow channel B2 anti-clogging performance improved by 30.8%. This study can provide a reference for further improving the hydraulic performance of drip irrigation emitters. [ABSTRACT FROM AUTHOR]

This article continues and generalizes the study "On the Similarity of Quasi-Geostrophic Vortices against the Background of Large-Scale Barotropic Currents" [6] (Oceanology, Zhmur, 2024, in print). In continuation of [6], a similar formulation is considered, but for other types of background currents. In the quasi-geostrophic description for small Rossby numbers, the problem of the evolution of an arbitrarily shaped liquid volume with homogeneous potential vorticity of all vortex core particles in an equidistant background flow—horizontal flow with vertical shear and equidistant flow with barotropic and baroclinic components—is presented. Ultimately, the problem boils down to an integrodifferential equation for the evolution of the vortex core boundary. The study of this equation in dimensionless form makes it possible to find a set of dimensionless parameters that determine the similarity condition of the studied vortices. [ABSTRACT FROM AUTHOR]

In this article, I suggest that our current relation to the sociopolitical future is one where we are blocked from changing our view of what that future is or could be. In this sense, we are trapped in a time loop wherein the challenges before us are continuously met with social and political solutions designed for futures past, old futures. These past possible futures are ones that failed to solve the problems they were offered to address. As such, there is no growth, change, or redemption that could activate a new future; there is only the rehearsal of the old ones: failed futures from the past. What's more, this process of defuturing also relies on a winnowing of the past such that only those pasts that align with our present are allowed to be brought forward. I argue that, to reactivate our future, we also need to reactivate our pasts. I am thinking of those pasts that we do not seek or do not want but that nevertheless come to us. These are the multiple and competing pasts that swirl with present and future as in a vortex, denying any one past the privilege of guiding, directing, or foreclosing the future. It is only by facing this vortex and reopening the past that we can re‐open the future and escape the time loop of our ever‐receding horizon. [ABSTRACT FROM AUTHOR]

Modern laver fluffiness is achieved by applying high-speed gas to a laver, which is generated by the opening and closing of a laver fluffiness control valve in a fluffiness system. To address the problems of the slow response speed and poor stability of valves used in the laver processing industry at present, this paper proposes a novel principle of a high-speed switching control valve, which has the advantages of a fast response speed, high stability, and long service life. The structure and working principle of the control valve are introduced, and the calculation equation of the valve's flow area is established. The flow field inside the control valve with different openings was numerically calculated in this study using Fluent. The flow regulation characteristics and flow field performance of the control valve were also analyzed. The results show that, with an increase in the valve opening, the influence of the flow area at the valve throttle on the valve flow rate was weakened. When the valve was opened, a vortex appeared in both the upper and lower cavities, and jet flow occurred at the throttle of the middle flow channel. As the valve opening increased, the pressure in the upper cavity reduced, while the pressure in the lower cavity increased. The vortex in the flow field intensified, and the jet phenomenon at the valve throttle gradually disappeared. At the same time, the main stream in the lower cavity gradually changed from an annular flow to a direct flow toward the valve outlet. Furthermore, the impact, collision, and vortex formation of the fluid caused energy loss of the fluid, leading to a decrease in the outlet flow of the control valve. [ABSTRACT FROM AUTHOR]

Unstable flows in the runner of water turbines, such as reverse flow, vorticity and flow direction transition, are the main factors causing increased losses and decreased efficiency, and changing the geometry structure in the downstream of the runner is an important means of mitigating these instabilities. The different flow fields downstream of runners induced by different locking nut structures are numerically calculated and verified by experimental results. The flow states are evaluated in terms of characteristic quantities such as pressure gradient, swirling flow, reverse flow, and vorticity. The results show a non-negligible effect of the locking nut, which leads to a more uniform pressure distribution, increases the descending speed of the reverse flow rate, and reduces the volume and strength of the vortex. The small locking nut significantly weakens the pressure gradient, reduces the top reverse flow zone, and decreases the vortex volume at the blade flow passage outlet and the size of the downstream disturbance vortex. The extended lock nut reduces the growth rate of the vortex generation rate and the size of the partial vortex, but increases the range of the high-pressure zone, causing the bottom reverse flow and increasing the vortex. [ABSTRACT FROM AUTHOR]

In this article, I suggest that our current relation to the sociopolitical future is one where we are blocked from changing our view of what that future is or could be. In this sense, we are trapped in a time loop wherein the challenges before us are continuously met with social and political solutions designed for futures past, old futures. These past possible futures are ones that failed to solve the problems they were offered to address. As such, there is no growth, change, or redemption that could activate a new future; there is only the rehearsal of the old ones: failed futures from the past. What's more, this process of defuturing also relies on a winnowing of the past such that only those pasts that align with our present are allowed to be brought forward. I argue that, to reactivate our future, we also need to reactivate our pasts. I am thinking of those pasts that we do not seek or do not want but that nevertheless come to us. These are the multiple and competing pasts that swirl with present and future as in a vortex, denying any one past the privilege of guiding, directing, or foreclosing the future. It is only by facing this vortex and reopening the past that we can re‐open the future and escape the time loop of our ever‐receding horizon. [ABSTRACT FROM AUTHOR]

It is shown that the front of the flame of a thoroughly mixed diluted methane-oxygen mixture at 298 K and 100–300 Torr propagating to the ends of hollow cylindrical and conical obstacles does not form a von Kármán path (vortex shedding) behind them; however, this instability occurs under the same conditions in the flow of hot products after obstacles. The reason that vortex shedding is not observed behind an obstacle during flame propagation but appears in the course of propagation of a reflected stream of hot products is that thermal conductivity reduces the curvature of the flame and leads to its stabilization. Indeed, the convex areas of the chemical reaction zone in a combustible mixture give off more heat in relation to cold ones than in a flat flame: the heat from them is not only transmitted forward in the direction of flame propagation but also in the lateral directions. The resulting cooling of the reaction zone causes the flame regions that burst forward to lag behind. The opposite situation is observed in concave areas, where the temperature rises for the same reasons. The rate of reactions increases and they spread forward faster as the flame spreads. Thus, the surface of the curved front of the flame is evened out. In other words, thermal conductivity has a stabilizing effect on a curved flame. This effect is missing in non-reactive gas. This effect is absent in a nonreacting gas. Calculations based on the acoustic approximation of the Navier–Stokes equations for a compressible reacting medium make it possible to take into account the main observed feature of the flame front approaching an obstacle in the form of a cylinder: vortex shedding is not observed behind the obstacle during flame propagation. Thus, a qualitative model allows obtaining both the mode of the emergence of a von Kármán instability in a chemically inert gas and its absence during flame propagation. [ABSTRACT FROM AUTHOR]

The spot-tailed earless lizards (STEL) are small, phrynosomatid lizards in the Holbrookia genus. Historically, these were considered two subspecies, the Plateau (Holbrookia lacerata lacerata) and Tamaulipan STEL (Holbrookia lacerata subcaudalis); however, each are now recognized as a distinct species (i.e., H. lacerata (plateau STEL) and H. subcaudalis (Tamaulipan STEL)). Recently, the plateau STEL was considered but not awarded federal protection under the Endangered Species Act by the U.S. Fish and Wildlife Service; however, much uncertainty remains about the status of the Tamaulipan STEL and a conclusive policy decision has not been made. In this study, we developed a hybrid theoretic-empirical demographic model and conducted a population viability analysis (PVA) of the Tamaulipan STEL (H. subcaudalis). We evaluated the role of multiple demographic, environmental, and anthropogenic parameters and assessed population-level effects and extinction risks via sensitivity experiments. The baseline simulation demonstrated that Tamaulipan STEL have a relatively low probability of extinction under best case scenario conditions; however, results of elasticity analysis of the baseline simulation and sensitivity analysis of demographic parameters demonstrated that increases in juvenile mortality had the greatest effect on population growth rate and extinction risk. Simulations of anthropogenic impacts showed that small increases in habitat loss (e.g., 2 %) had drastic negative effects on population size and persistence. Results from this study demonstrate the need for conservation and management actions aimed at protecting and increasing populations of young individuals (i.e., decreasing juvenile mortality) and promoting the conservation of available and suitable habitat for STEL throughout their range. These results must be considered in future conservation initiatives focused on this species to achieve successful conservation outcomes.

To study the breakup process of fuel jets in air crossflow with a positive velocity gradient, the Volume of Fluid (VOF) method and adaptive grid technology are combined to simulate the two-phase flow of gas and liquid. A comparative analysis is conducted on the breakup and corresponding flow characteristics of direct fuel jets under uniform and positive velocity gradient airflow. The simulation results demonstrate that the morphological changes of the fuel column are caused by factors such as gas-liquid shear and asymmetric airflow vortices. The fuel jet undergoes primary breakup, which mainly contains columnar and surface breakup. The columnar breakup is dominated by Rayleigh-Taylor (R-T) instability, while the surface breakup is dominated by Kelvin-Helmholtz (K-H) instability. Compared with uniform flow, the expansion angle in the positive velocity gradient incoming flow increases by an average of 9.2%, and the wavelength of the surface wave increases by an average of 34%.

This paper focuses on a numerical study about the stochastic Navier–Stokes equations. Unlike previous studies, this paper focuses on studying these equations from the perspective of vortices. The vorticity–stream function method was proposed to deal with incompressible fluid flow. And a Crank–Nicolson Fourier pseudo-spectral method was put forward to solve the formulation of stream function equation. In addition, we have conducted some numerical experiments to observe the effects of random forcing on vortices in the fluid flow by utilizing stochastic solution.