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The study of non-stationary vortex structures arising at the inlet of centrifugal pumps and at the outlet of turbines of the Kaplan and Francis type is the subject of the presented paper. Specific attention will be paid to spatial vortices, characterized by curvature and twist. Spiral vortices will also be monitored as sources of spatial vortex motion. Their core will be expressed by a mathematical model in curvilinear coordinates. Helicity, which indicates the degree of vorticity, will also be determined by computational simulation of turbulent motion. The swirling motion will be induced by a specially designed diffuser-shaped vortex generator, simulating the inlet to the turbine draft tube. A significant result of the study of vortex structures will be the dependence of the twist of the streamline in relation to the Hessian matrix, expressed as a function of the pressure function. This dependence will be significant for the optimization of the hydraulic machines. [ABSTRACT FROM AUTHOR]

In this paper, we provide an exploration of the interrelated topics of chirality, vorticity, and spin polarization in relativistic heavy ion collisions. Our discussion delves into the intricate relationships among these phenomena, examining the recent measurements conducted at both RHIC and LHC.We review the challenges faced, the progress made, and the current state of understanding regarding hot QCD matter under rotation. [ABSTRACT FROM AUTHOR]

The Spalart-Allmaras (SA) turbulence models applied to the calculation of swirling flows inside a separator was studied. Two approaches using vorticity and flow function to eliminate pressure and a semi-implicit method for pressure-linked equations (SIMPLE) for solving Reynolds-averaged Navier-Stokes equations were compared in the article. For the numerical solution of both approaches, the implicit method against the flow was used. [ABSTRACT FROM AUTHOR]

Out of the analytical results of the innovative paper [1] by r.meulens becomes it clear that the solutions for the (in)compressible Navier Stokes differential equations are locally curved. Since the N-soliton based vorticity and velocity tensors solutions are directly and tangentially related to the space-like and time-like variables of non-linear wave-phenomenons, implicates that the last variables are also curved in the benchmark analyzed problems. Using the buoyancy model principles of Archimedes and the compressible and viscid Navier Stokes d.e. it became clear that the (artificial) gravity is velocity dependent and therefor quantized and can be calculated out of the solutions presented in [1] The velocity is a solution of the Eigenvalue problem of a quantum harmonic oscillator. This article gives the necessary building stones to introduce the omne mechanicae for the unification of the four forces in nature in one set of momentum, continuity equations (as modeled by the Navier Stokes d.e.) complemented with situational state equations depended on the thermodynamical conditions of the sample volume. This article also addresses and does explain some other unsolved paradigms of physics like the information paradox and the problems with the cosmological constant which are automatically solved with the introduction of the Navier Stokes d.e.to model cosmological processes. [ABSTRACT FROM AUTHOR]

Fluid Structure Interaction (FSI) analysis for fluctuating beam in viscous fluids has been carried out for the preliminary design of propeller-less underwater drones. The Immersed Boundary Method has been used to address a large variety of Fluid Structure Interaction problems such as insect flight, locomotion of fishes and batoid pieces etc.IB2d is an open-source MATLAB code developed by Battista, which can be used for solving two-dimensional Fluid Structure Interaction problems using the Immersed Boundary Method. The settings of IB2d solver have been verified by reproducing a flapping beam problem. The parameters for this problem have been changed to study the flow generated around a beam tethered at both ends and subjected to a perturbation of the beam in static fluid. The beam has been modelled as a setof Lagrangian points for a given length and stiffness value and the fluid around the beam is modelled as a Eulerian regionof certain viscosity and density. The beam has been perturbed from its equilibrium position by an ellipsoidal arc and the dynamics of vortices around the beams are analyzed both qualitatively and quantitatively. The simulations have been repeated by varying viscosities of the Eulerian region, varying length of the beam and varying stiffness values betweenthe Lagrangian points. The parametric study shows that the magnitude of vorticity around the beam reduces with increasein viscosity and stiffness It is also found that for the same curvature, the motion speed reduces with reduction in the beamlength. [ABSTRACT FROM AUTHOR]

Entropy inhomogeneities and vorticity spots induce so-called indirect combustion noise when passing through a choked nozzle; referred to as entropy noise and vorticity noise, respectively. We note that vorticity noise depends on the orientation of the vorticity; viz., oriented normal or parallel to the axial main flow. An experimental investigation of parallel component vorticity noise is presented. In the experiment a time-dependent swirling flow was induced by unsteady tangential injection in the pipe upstream of a choked convergent-divergent nozzle. As the resulting swirling flow passes through the nozzle, the axial stretching of the fluid caused an increase in rotation energy. The steady energy conservation in an isentropic flow implies a Mach number higher than unity at the throat and an associated reduction of density. Ergo, the critical mass-flow rate (for fixed reservoir pressure and temperature) decreases quadratically with increasing swirl intensity. The acoustic waves radiated downstream of the nozzle are due to the change in the mass flow through the nozzle. These are a direct measure for this mass-flow modulation. Using a semi-empirical model, this sound production mechanism is demonstrated to be quasi steady. This contradicts the bare assertion found in the literature that sound is produced by the acceleration of vorticity or "vorticity waves.". [ABSTRACT FROM AUTHOR]

The synoptic-meso-a scale study of a convective line shows that the latter was favored by the vertical superposition of the passage of an ULFnt onto a low-level convergence line. [ABSTRACT FROM AUTHOR]

Operational reliability and smooth functional performance of centrifugal pumps is related with the pumping unit and inlet hydraulic geometry conditions. Operational difficulties normally occur at site and lab performance is generally smooth during the shop testing of the pump. Pump suction arrangement is having major effect on the pump operating conditions. Numerical simulation and actual model testing is important to check the suction conditions for pump operating performance. Hydraulic geometry is maintained by optimally designing the inlet equipment's and hydraulic geometry in the flow path. Model study is conducted by the optimization of the hydraulic geometry using the inlet equipment's. These studies are concerned with experimental and hydraulic simulation of the pump sump design parameters. Flow is maintained, guided in the sump and vortex dissipating devices are installed in sump. These hydraulically optimized sump profiles having similarity for model study and flow simulation. This resulted in the smooth flow behavior and smooth performance parameters. Vorticity is reduced in the pump sump and having minor effect near the entrance of the flow in the inlet geometry and effect is reduced near the pump. The slight surface recirculation is not affecting the pump flow and operating condition. The experimental analysis is conducted on the scaled model and flow analysis is done with the actual geometry for hydraulic design of the pump sump. [ABSTRACT FROM AUTHOR]

Since the observation of Λ global polarization at RHIC, indicating the most vortical fluid ever observed so far, many experimental and theoretical progresses have been made in understanding of vorticity and polarization phenomena in heavy-ion collisions. But there still exist open questions which are currently being studied. In these proceedings, recent experimental results on global and local polarization of hyperons in heavy-ion collisions are reviewed. [ABSTRACT FROM AUTHOR]

Heavy accumulation of liquid in the gas pipeline results in formation of a water lute in the pipe. Periodic disturbing flow directed across the main flow leads to the generation of pulsating vorticity on the inner surface of pipes. The flow of multicomponent systems in pipes under pressure and density pulsating of a gas-liquid mixture was investigated using a drift model for the problem of the bubble flow mode in a long pipe.In order to reduce the risk of accidents and improve the efficiency of the gas pipeline, it is proposed to give the transported medium viscoelastic properties, using new technological schemes for control the dynamic parameters of the flow. [ABSTRACT FROM AUTHOR]

The existence of a reverse von Karman street behind a flapping airfoil has been identified previously. The present paper numerically investigates the path through which the reverse von Karman street is established. The investigations are performed over a custom-designed airfoil performing combined motion of pitch and heave. The wake transformation path is established by increasing the flapping frequency and amplitude while visualizing the structure of the wake. The wake structure behind the flapping airfoil is identified using contours of vorticity, and the structures are arranged categorically. The force coefficients at different flapping frequencies and amplitudes are computed, and their influence on propulsion performance is assessed. The variation in wake structure behind the flapping airfoil appears to influence the force experienced by the airfoil significantly. The transition of the wake from periodic dynamics to aperiodic dynamics reduced the propulsion efficiency of the airfoil. [ABSTRACT FROM AUTHOR]

Two buildings differing in height in tandem configuration are subjected to a turbulent boundary layer flow. The physical modelling in a wind tunnel has been performed, Particle Image Velocimetry in horizontal planes has been applied. The time-mean flow-field is dominated by the contrarotating vortex pair in the near-wake of the upstream building forming strong back-flow in this wake. Dynamical activity is located close to the bigger downstream building below the level of the smaller building roof. The dynamical structures in the space between them are studied using advanced analytical methods, Oscillation Pattern Decomposition (OPD). The 3 important OPD modes were detected differing by topology and frequency. The 2 OPD modes are characterized by vortical structures formed within the wake of the smaller upstream building and moving downstream towards the bigger building. The last OPD mode shows strong pulsation transversal flow in front of the bigger building. Typical frequency of the cyclo-stationary behaviour could be characterized by the Strouhal number in the range from 0.09 up to 0.15. [ABSTRACT FROM AUTHOR]

LHCb has the unique capability to operate in fixed-target mode to study collisions of the LHC beams on fixed targets. In Run3, the internal gas target is going to be upgraded to allow for a wider selection of target gas species and a significant increase of the rates of fixed-target collisions by up to two orders of magnitude. Along with significant data acquisition and tracking upgrades, the SMOG2 system greatly enhances the reach of LHCb's heavy ion program. [ABSTRACT FROM AUTHOR]

We study the propagation of charm quarks in the quark-gluon plasma (QGP) by means a relativistic Boltzmann transport (RBT) approach coupled to electromagnetic field. The interplay between these fields is responsible to generate large rapidity odd directed flow v1 of D mesons and for a large splitting of directed flow Δv1 between neutral D and anti-D mesons. We show that the large v1 is generated by the longitudinal asymmetry between the bulk matter and the charm quarks and by a large non-perturbative interaction in the QGP medium. [ABSTRACT FROM AUTHOR]

We propose an improved quark coalescence model for spin alignment of vector mesons by spin density matrix with phase space dependence. Within this model we propose an understanding of spin alignments of vector mesons ϕ and K*0 in the static limit: a large positive deviation of ρ00 for ϕ mesons from 1/3 may come from the electric part of the vector ϕ field, while a negative deviation of ρ00 for K*0 mesons may come from the electric part of vorticity fields. In the low-pT region, ρ00 for K*0 mesons is proportional to pT2 $p_T^2$ p T 2 , which is qualitatively agree with experimental results. [ABSTRACT FROM AUTHOR]

In non-central nuclear collisions, the created matter should exhibit strong vorticity, which induces spin polarization. Global polarization is a good tool to investigate the dynamics of the system. Global polarization of Λ and Λ¯ ${\bar \Lambda }$ Λ ¯ hyperons has been measured at √SNN = 2.4 GeV - 5.02 TeV $\sqrt {{S_{{\rm{NN}}}}} = 2.4\,{\rm{GeV}}\,{\rm{ - }}\,{\rm{5}}{\rm{.02}}\,{\rm{TeV}}$ S NN = 2.4   GeV   -   5.02   TeV in various experiments. We have measured the global polarization of Λ hyperons in Au+Au collisions with fixed-target configuration at √SNN = 7.2 GeV $\sqrt {{S_{{\rm{NN}}}}} = 7.2\,{\rm{GeV}}$ S NN = 7.2   GeV at RHIC-STAR experiment. The non-zero signal is observed and it follows the global trend of Λ global polarization that increases towards lower collision energies. The global polarization is larger in more peripheral collisions but it does not show any significant rapidity dependence as well as transverse momentum dependence within uncertainties. [ABSTRACT FROM AUTHOR]

Recent experimental results on global polarization of hyperons and spin alignment of vector mesons in heavy-ion collisions are reviewed, especially in context of the energy dependence and particle species dependence. New results on local polarization along the beam direction at the LHC are discussed with previous measurements at RHIC. Future outlook of these measurements and possible future directions for better understanding of local vorticity field are briefly discussed. [ABSTRACT FROM AUTHOR]

The interplay between classical vorticity being the main undisputed source of polarization in heavy-ion collisions (HIC) and quantized vortices is considered. The vortex tubes emerging in the rotating pionic (super) fluid polarize the baryons in their cores and explain the emerging global polarization. The appearance of vortices in the region separating participants and spectators in non-central HIC is similar to that for sliding layers of liquid helium. From the other side, it is also the region where the classical vorticity was earlier found to be large forming the vortex sheets. The formation of tubes manifests a threshold at certain critical vorticity implying the vanishing polarization at lower energies. For central HIC the compact jet-like flows may lead to formation of vortex rings related to local polarization. The P-odd momentum correlations for their experimental investigation are suggested. The role of shear and viscosity in the emergence of polarization is discussed. [ABSTRACT FROM AUTHOR]

When the forces act on a bluff body in the wind flow direction, vortices are formed. Vortex bladeless wind turbine oscillates as a result of the vortices generated due to VIV. When the vortex shedding frequency is nearer to the natural frequency of the structure, maximum amplitude of vibration occurs and coincidentally power is generated. 3D models are designed to stimulate flow at a Reynolds number of 50000. This paper focuses on modelling the bladeless wind turbine based on semi-vortex angle and also 1) to study the vortices pattern and vorticity of different models 2) to study the drag and lift coefficients. In this paper vortex turbine is designed with certain parameters of dimension in Solid Edge and CFD analysis is carried out in Simscale software. Different model performance parameters like power, natural frequency and coefficient of power are compared among different models to opt for the best vortex bladeless wind turbine design. [ABSTRACT FROM AUTHOR]

High fidelity interactions between game characters and gaseous effects like smoke, fire and explosions are often neglected in real-time applications due to the high computational cost of simulating fluids. In addition, the pose of game characters is only known at runtime as it depends on input from the user. Thus simulation-suitable representations of surface geometry must be generated on the fly. Common approaches like conversion into signed distance fields are not feasible for high-resolution geometry due to the computational cost and the amount of memory required on the GPU to store these fields. We present a purely vortex particle based fluid model for games which is capable of resolving the collision between fluids and complex objects such as moving game characters in real time. To handle collisions, we use a collocation method which only require a set of disassociated particles stuck to collision surfaces. Contrary to most other vorticity based methods, we use a simple inversion free approach to obtain the collision velocity field on surfaces while at the same time avoiding the expensive pressure projection step associated with pressure based fluid solvers. [ABSTRACT FROM AUTHOR]

Numerical models of granular materials are useful in tribology, and can be used to predict wear and friction in contacts. DEM-like simulations are used to model particles of third-body, which are partly wear debris from rubbing bodies. It has been shown that the third-body particles can have different flow regimes, depending on their mechanical properties. Among the different characteristics of flow regimes, agglomerate size seems to be crucial. A method based on vortex analysis used in fluid mechanics allows characterizing this cluster size. The results show that different vortex sizes can be observed during the simulation. In particular, it is observed that some vortexes of a characteristic size persist over time, and could be representative of agglomerates. These results pave the way for a better characterisation of the different flow regimes. [ABSTRACT FROM AUTHOR]

Displacement fields in sheared particle packings often display vortex-like structures that reveal essential features about the mechanical state of the collection of particles. There are several metrics to quantify these flow field features, yet extracting such quantitative metrics from flow field or particle tracking data involves making numerous choices on the time and length scales over which to average. Here we employ a much used experimental data set on sheared disk packings to explore how such arbitrary data mining choices affect the obtained results. We focus on calculating the strain dependent vorticity, as this metric is a differential method hence potentially sensitive to the way it is computed. We find that the total surface area with an absolute vorticity above a certain threshold approaches a plateau value as shear progresses. This plateau value exhibits a non-monotonic dependence on packing fraction. We also show which range of choices yields results that can support an analysis method independent, physical interpretation of the flow field data. [ABSTRACT FROM AUTHOR]

We report on a numerical simulation of morning transition in the atmospheric boundary layer above the river Yenisey near the city of Krasnoyarsk. The effect of meandering river promotes complex air circulation patterns leading to the formation of large-scale vertical vortex pair. The current LES results supports previous RANS simulations indicating the vortices positions at the minimum curvature points of the meander. The vortices affect the humidity distribution leading to uneven spreading of the water vapour along the river banks. The convective vortex pairs (rolls) are attracted toward the river during the morning ground heating. The vorticity which is transferred with these pairs is feeding the main vertical vortex. This feeding process is responsible for the large vortex stability. [ABSTRACT FROM AUTHOR]

A promising scientific direction in aerohydromechanics related to structure control is discussed. The combination of structural elements with generated jet-vortex structures makes it possible to intensify the transfer processes and sometimes radically improve the aerodynamic and thermophysical characteristics of technical and energy systems. As examples, we consider the control of the flow around thick bearing surfaces when changing the position of the vortex cell using the throttling effect to intensify the flow circulating in the cell, as well as anomalous intensification of the separated flow and heat transfer in dense single-row packets of oval-trench dimples on the wall with varying orientation angle dimples to a turbulent flow in a narrow channel. The stabilization of the flow around a thick 37% Göttingen airfoil with the location of the vortex cell in the trailing edge region is established. Turbulent heat transfer in a narrow rectangular channel 7 to 1 was calculated on a stabilized hydrodynamic section at Re = 3333 with a single-row OTL packet with a depth of 0.25 with a step between dimples 3. The influence of the oval-trench dimples inclination angle θ in the range from 30° to 56° was analyzed. The angle θ of about 55° is close to optimal, and the relative thermal efficiency approaches 100% with a 55% increase in hydraulic losses. The optimal angle θ corresponding to the highest thermohydraulic efficiency turned out to be close to 48°. The local maximum of the 4-fold increase in the relative heat transfer coincides with the local maximum of the static pressure inside the separation zone in the area of increasing relative friction after it reaches its minimum values, reaching -3.4. [ABSTRACT FROM AUTHOR]

The equilibrium magnetization configurations and the associated microwave susceptibility spectra of dipolar coupled nanoplatelets are explored using three-dimensional (3D) micromagnetic simulations. First, the case of periodic arrangements of nanoplatelets on square arrays is considered. As a result, a macro-vortex state defined as a flux closure pattern spreading over the whole array with or without a vortex core can be stabilized starting from an initial orthoradial magnetization configuration. For macro-vortex states with a vortex core, the linear excitation spectrum exhibits a sub-GHz resonance line ascribed to the vortex core dynamics at the array center. The features of this line (spectral position and amplitude) depend on the array size and the strength of the dipolar coupling through the interplatelet spacing. This resonance is also observed for macro-vortex states without a vortex core but only in the regime of a strong dipolar coupling. The effect of disorder is then investigated by numerically generating assemblies of nanoplatelets with a position disorder and, shape and size distributions. The micromagnetic simulations reveal flux closure magnetization configurations as well but without a vortex core. A low-frequency resonance appears in the susceptibility spectra for quite high surface contents of nanoplatelets but its amplitude is weaker compared to the case of periodic arrays. This line arises from a collective mode extended over a few nanoplatelets. A large variety of static and dynamical behaviors is thus evidenced resulting in a great complexity even in such model systems. [ABSTRACT FROM AUTHOR]

Langevin simulations of cubic magnetic nanodots were performed using the Landau-Lifshitz equation with exchange and dipolar interactions. Vortices tend to organize as lines: we establish the structure and dynamics thereof for a large range of the dipolar versus exchange ratio d. These lines tend to be bent and twisted. For large values of the dipolar interaction, a complex network of vortex lines arises. Dynamics evidences low frequency collective gyrotropic motions of vortex lines which maintain their distance during motion. [ABSTRACT FROM AUTHOR]

This research paper explains the generation and evolution of a Newtonian fluid droplet through the computational simulation. The volume of fluid method is adopted to capture the dynamic mechanism of the droplet. The results show how the physical properties of the continuous phase affect the drop formation, breakup length and volume of droplet. The pressure variation at the detachment stages is also examined. Also, studies the difference in the vorticity distribution around the droplet generated in two different phase conditions. [ABSTRACT FROM AUTHOR]

The wake behind a wall-mounted finite-length circular cylinder of the aspect ratio 2 stuck out of a wall was studied experimentally using stereo PIV technique. The cylinder was mounted normal to a ground plane and it was subjected to a cross-flow with thin boundary layer developed on the wall, the Reynolds number based on inflow velocity and cylinder diameter was 9.7 thousands. The time-averaged velocity and streamwise vorticity fields showed the development of the mean flow structure consisting of the tip vortex pair, the extent of the near-wake recirculation zone with back-flow, the downwash phenomenon and base vortex structures close to the wall. [ABSTRACT FROM AUTHOR]

In the current work we assess numerically by LES to which extent the active control device, i.e., axial velocity oscillator changes the structure of the 30 turbulent two-phase flame by actuating the flow with specified frequencies. The outcomes show that the jet velocity forcing resulted in nonlinear and direct impact on the flow field close to the inlet plane by modifying the mean vorticity field. Secondly, it influenced the mixing rates of the evaporating species. Finally, the velocity oscillations influenced the droplets dispersion. It was found that indirectly, the oscillations influence the combustion process by altering the flame lift-off and mean temperature through changes in the mean mixture fraction field. [ABSTRACT FROM AUTHOR]

Three-dimensional computations have been carried out to investigate the effect of aspect ratio on wake characteristics of a prolate spheroid. Open source LBM solver (Palabos) has been used for the computations after obtaining necessary validations. Three different aspect ratios, namely, 1:2, 1:4 and 1:6 have been considered in present study for a fixed Reynolds number (Re) of 200. Wake remains unsteady for all aspect ratios at this Re. The coherent structures in the wake (vortices) have been identified using instantaneous plots of Q-surface, vorticity contours and line integral convolution. These results indicate transition of wake from steady three-dimensional to unsteady three-dimensional with the increase in aspect ratio. [ABSTRACT FROM AUTHOR]

Numerical analysis to investigate the flow characteristics of non-Newtonian power-law fluids across a roughened circular cylinder has been done using ANSYS Fluent 18.0. The Reynolds number (Re)and power-law index (n) of the flow vary in the range of 1 ≤ Re ≤ 40 and 0.25 ≤ n ≤ 1.5 respectively. The flow characteristics have been analyzed in terms of pressure (Cdp), friction (Cdf) and total drag coefficients (Cd) withRe and n as variable parameters. The detailed flow visualization has been done with the help of streamlines and vorticity contours. All else being similar Cdp and Cdf decrease with Re. The Cd for dilatant fluid is less than the Newtonian fluid for Reynolds number up to 10, whereas, for Re > 10, the Cd for Newtonian fluid is less than the dilatant fluid, under otherwise identical situations. Cd on the roughened circular cylinder is significantly higher than the simple circular cylinder. [ABSTRACT FROM AUTHOR]

Computational study of flow and heat transfer characteristics from a rotating circular cylinder kept in cross-flow is performed. The interaction between inertial and thermal forces strongly affects the wake of the circular cylinder. To study this interaction, the cylinder is kept in a cross flow corresponding to Reynolds number in the range of 50 to 200, and is heated so that the Richardson number is 1. The rotation rate is varied between 0 to 2, and its effect on wake was studied. It was found that with increase in rotation rate the variation of average Nusselt along the cylinder surface becomes more uniform. This uniformity is achieved on behest of reduction in heat transfer which can be attributed to the negative vorticity generation due to rotation of the cylinder. [ABSTRACT FROM AUTHOR]

Water tunnel (WaTu) visualization techniques have been in high demand to analyze aerodynamic characters in the delta-aircraft model because of clearer and more detailed results. The visualization was used to observe the aerodynamic characteristic of the rolled-up vortex phenomenon on delta-wing. The difference in fluid and flow parameters became an issue of the accuracy of the results. Therefore, testing parameters need to be analyzed so that the results of the WaTu test have been able to represent the real conditions. This research has varied the velocity to investigate the delta-wing aerodynamic characteristics using GAMA water tunnel. The results were compared with computational fluid dynamics (CFD) results based on WaTu and real (subsonic) conditions, as well as several other references. The results showed a similarity in the vortex breakdown location (VBL) at all flow rates in the WaTu and CFD. The CFD results also showed that the coefficient of pressure (Cp) on the wing had the same results in all tests, both based on WaTu and real conditions. Likewise, for a lift and drag coefficient (Cl-Cd), values for all states approached the same amount with a difference of less than 5%. Finally, the uses of the WaTu method has been able to represent the actual conditions in vortex dynamics cases in delta aircraft with the optimum velocity to produce the best visualization around 0.1 m/s. [ABSTRACT FROM AUTHOR]

Within the framework of eddy-resolving simulation, this paper aims to study the potential of two advanced turbulence modeling approaches in resolving turbulence scales over a reference geometry. Two k-ω SST based-scale resolving schemes are applied on a circular cylinder with a splitter immersed in turbulent flow at a sub-critical Reynolds number of around 3 x 104. The scale resolving computations starts with RANS predictions using the SST model where spatial and temporal grid studies are to be performed to craft the numerical mesh resolution required. With a standard k-ω SST model the results of the spatial and temporal grid sensitivity studies on the 2D domain give optimum mesh and timestep size to demonstrate the Strouhal number of 0.238 and unsuppressed vortex shedding after the rigid splitter. The vortex shedding phenomenon was also proven in an experimental study with a similar Reynolds number and equivalent ratios of splitter thickness and length to the cylinder diameter of 0.09 and 2.72, respectively. Under the optimum mesh and timestep size, comparison of the Strouhal number on 2D and 3D domains with one of the experiment is also performed, serving as a baseline point to modify the production of turbulent kinetic energy term in the k-transport equation of the standard k-ω SST model in order to evade an excessive generation of the turbulent kinetic energy due to the existence of a stagnation region ahead of the cylinder. On the 3D domain with the numerical ingredients, the computational results obtained with a modified k-ω SST model provide an encouraging result closer to the experimental data, giving the Strouhal number of 0.234. To study the inherent strategies in the two vorticity resolving schemes, the highest levels of the spatial and temporal grids are used. This is crucial to detect whether or not the finest mesh is prone to a numerical problem in one of the scale resolving formulations. During this stage, the ratio of the grid length scale to the RANS integral length scale, which is the functions of the turbulent kinetic energy and dissipation, in critical regions is scrutinized to be less than 0.1 – 0.2 to maintain high-quality mesh. The numerical results from the modified k-ω SST based-hybrid RANS-LES proposals suggest a prospective approach based on the modification of the dissipation term in the k-transport equation to be used even with a coarser grid, which is able to resolve turbulence scales on the configuration. The Strouhal number of 0.189 predicted by the superior model is close to a reference value in the experiment. The weakness and strategy in each scale resolving scheme are discussed within the context of crucial issues in the progress of the non-zonal hybrid RANS-LES models. [ABSTRACT FROM AUTHOR]

Effects of viscosity on wave propagation in swirling jets are examined. The swirling jet is modeled by a tophat axial velocity profile, with a constant axial vorticity in an unperturbed state. The jet is surrounded by an irrotationally revolving inviscid incompressible fluid (i.e. potential flow). An exact solution of the given linearized problem in the form of a partial inertial wave is presented. The velocity and pressure fields in the core can be expressed through the superposition of partial waves. Normal mode analysis leads to an eigenvalue problem which is reduced to find the roots of the dispersion transcendental equation. We conduct the stability analysis based on this dispersion equation. [ABSTRACT FROM AUTHOR]

A vorticity field in two parallel counter-swirling submerged jets of viscous incompressible fluid is studied in laminar and turbulent regimes. A mechanism of a quadrupole longitudinal vorticity field generation under a confluence of two laminar jets into one is described. An analytical expression for a far-field of the longitudinal vorticity is obtained. Direct numerical simulation of two turbulent jets interaction is carried out. The invariants of the flows are constructed. [ABSTRACT FROM AUTHOR]

The possibility of designing a porous medium that mimics an acoustical perfectly matched layer (PML) is discussed. In numerical methods, a PML provides essentially zero reflection and rapid attenuation in space. As a starting point to designing such a medium, the relaxation-model equations (10.54) and (10.55) from V. E. Ostashev and D. K. Wilson [Acoustics in Moving Inhomogeneous Media, CRC Press, Boca Raton, 2016] are employed. In general, it does not appear to select the parameters to mimic a PML across a range of frequencies. For relatively high frequencies, however, it is shown that by setting the ratio of the vorticity and entropy shape factors to (Npr) 1/2/(γ-1), where Npr is the Prandtl number and γ is the ratio of specific heats, the impedance becomes real-valued while the medium remains attenuative. Possible approaches are discussed for adjusting this ratio based on varying the pore shape, the cross section, and the pore-size distribution. However, it does not appear to be possible to make the ratio less than one, as would be necessary to realize the PML condition in air and other fluids. [ABSTRACT FROM AUTHOR]

The role of vorticity and acceleration in relativistic hydrodynamics is investigated. Particular attention is paid to the effects of vorticity, as well as mixed effects, when the medium has both acceleration and vorticity. Quantumfield corrections to the energy density of free Dirac fields are calculated using the Zubarev density operator. The corresponding nonperturbative formulas are proposed and justified in the particular cases of parallel vorticity and acceleration and zero acceleration. [ABSTRACT FROM AUTHOR]

We report our micromagnetic simulation investigation of the magnetic vortex core motion in a disk with an antidot. With variation of antidot geometry, faster core gyration is expected, where gyrotropic motion near antidots becomes quite sensitively depending on the antidot geometry, with frequency up to several GHz. Our finding opens a possibility to boost up the core motion of a ferromagnetic nanostructure with introducing geometrical modulation. [ABSTRACT FROM AUTHOR]

Using the construction of several particular exact solutions, the article investigates the overdetermined system of equations of thermal convection of a vertically swirling viscous fluid in the Boussinesq approximation. The vertical component of vorticity in a non-rotating fluid is generated by an inhomogeneous velocity field at the lower boundary of the infinite horizontal fluid layer. The main causes of convection in the problem under consideration are linear heat sources and the field of shear stresses. The main attention is paid to the study of the properties of the flow velocity field and the dependence of the structure of this field on the magnitude of the vertical swirl. [ABSTRACT FROM AUTHOR]

A new exact solution of the layered convection problem is considered. The obtained solution describes the flow layer of a viscous incompressible fluid with nonzero gradients of temperature and pressure. The horizontal velocity components depend only on the vertical transverse coordinate of the fluid layer. At the lower layer boundary, nonzero temperature gradients and the Navier slip condition are specified, tangential stresses and longitudinal pressure gradients being specified at the upper boundary. The possibility of the occurrence of counterflow areas and the corresponding changes in the tangential stresses and the vorticity vector are shown for the obtained particular exact solution. [ABSTRACT FROM AUTHOR]

The paper is the first to theoretically derive plastic rotations (vorticities) caused by dynamics of translational defects. The sources of plastic rotations are elastic rotations determined by defects. It is shown that motion of defects causes medium structuring, that is, formation of “structural elements” with eigenfrequencies and dimensions determined by physical parameters of the material. Elastic rotational oscillations with a frequency less than the eigenfrequency of a structural element are not perceived by the medium. By the example of a one-dimensional problem solution, it is shown that the phenomenon of resonance takes place, if the eigenfrequency of elastic rotations of a structural element coincides with one of the eigenfrequencies of plastic rotations due to boundary conditions. The obtained results contribute to the understanding and theoretical description of the phenomenon of fragmentation. [ABSTRACT FROM AUTHOR]

There are various techniques for water purification but solar still is the cheapest and beneficial one. Solar stills are easy to construct, and the material is readily available. Knowing that the productivity and efficiency of the conventional solar still is too low has led the researchers to develop new techniques and advancements. This Numerical study investigates the influence of constant and variable temperature difference on condensing and evaporating surfaces with and without baffle on single slope solar still. Besides this, a sensitive analysis was carried out on the positioning of baffle at 1/3rd, 1/2nd and 2/3rd from the left side of still. The flow structure, velocity contours with magnitude, vorticity magnitude and temperature contours have been plotted. The convection heat transfer has been estimated which are tabulated and plotted against Rayleigh number to identify favorable and adverse flow pattern to optimize the productivity of the solar still. [ABSTRACT FROM AUTHOR]

In this paper, we consider the numerical solution of the vorticity transport equation (V.T.E.), which is the basic non-dimensional nonlinear parabolic partial differential equation that governs unsteady flow problem, in two dimensions. We study the alternative direction implicit (A.D.I.) finite difference formula, which can be used to compute the numerical solution for this equation with zero Dirichlet boundary conditions. Moreover, the consistency and the stability of this scheme are discussed. Finally, the approximate solutions and simulations are carried out for a numerical experiment with certain initial functions. [ABSTRACT FROM AUTHOR]

In this work, bottom outlet which is a part of dam that functional to flow a water. The design of bottom outlet is constructed by Computer-aided design (CAD) modelling and simulated using Computational fluid dynamic (CFD) software. The effect of water flow pattern, velocity and vorticity of the bottom outlet has been analyzed in this research work. Based on the result, the peak velocity occurs at the middle area of bottom outlet with amount of 146.8430 m/s and vorticity occurs at the end of bottom outlet with velocity of 16.3159 m/s. [ABSTRACT FROM AUTHOR]

The global flow-field around an airfoil will be studied using time-resolved PIV technique. Interactions between pressure and suction sides flows will be studied in detail. Spanwise structures dynamics is to be analysed. [ABSTRACT FROM AUTHOR]

Highly turbulent flows above variously rough surfaces were investigated by means of Time-Resolved Particle Image Velocimetry in a wind tunnel. Proper Orthogonal Decomposition was applied to both velocity and vorticity data in order to detect dominant features in the flow based on turbulent kinetic energy and enstrophy, respectively. While both the shape and location of the POD patterns exhibited similarity with other studies, a systematic inconsistency in terms of contribution from the features to the enstrophy between the previously published papers and our results were found. [ABSTRACT FROM AUTHOR]

Initial large global angular momentum in non-central relativistic heavy-ion collisions can produce strong vorticity, and through the spin-orbit couping, causes the spin of particles to align with the system's global angular momentum. We present the azimuthal angle dependent (relative to the first-order plane) global polarization for Λ hyperons in midcentral Au+Au collisions at S N N $ \sqrt {S_{NN} } $ = 200 GeV. We also present the polarization of Λ hyperons along the beam direction as a function of Λ hyperons' emission angle relative to the second-order event plane at S N N $ \sqrt {S_{NN} } $ = 200 GeV. This longitudinal polarization is found to increase in more peripheral collision. The implications of the results are discussed. [ABSTRACT FROM AUTHOR]

The paper deals with the scattering of linear polaritons on the incoherently excited stationary states. By direct numerical simulations it is shown that the vorticity of the stationary nonlinear polariton state can be probed by propagating polaritons of low intensity. It is discussed how the influence of the vorticity of the nonlinear state on the probe signal can be used for the characterization of the polariton states and for the design of polariton interferometers. [ABSTRACT FROM AUTHOR]

We probe vortex dynamics in a thin film superconductor non-locally, i.e. away from the point where an electric current is applied. Lorentz force decreases along vortex motion and so does the vortex velocity. We also propose to perform voltage measurements concerning additive and cancelling flux flows at these non-local points. By analyzing minimal data that has been published previously we see that non-local flux dynamics is very different compared to usual flux dynamics with regions of decreasing resistance in increasing current. This point outs new dynamical aspects in vortex transport. Apart from this our studies are for those who wish to image slow vortices using scanning probe techniques. [ABSTRACT FROM AUTHOR]