Vortex Decay Research Articles

Intraventricular blood flow with a fully dynamic mitral valve model

Mitral valve (MV) leaflets affect the formation, growth, and decay of vortices in the left ventricle (LV) during diastolic filling. The shape and motion of MV leaflets are simplified in most studies due to computational restrictions. In this study, we present a newly developed mathematical method to model the dynamic movement of valve leaflets and annulus, which is based on in vivo data obtained with magnetic resonance imaging (MRI). In the present method, we solve a boundary value problem where the MV surface is initially unknown. The resultant MV shapes are included in a dynamic motion model of the LV to assess the change of intraventricular flow patterns. To estimate the effects of the MV on left intraventricular flow, a LV model without MV leaflets was also simulated for comparison. Our study showed that the presence of the MV and the shape of its leaflets significantly altered the formation and evolution of vortex structures in the LV. The various MV leaflet shapes accelerate the transvalvular flow distinctly, leading to different formation and development of vortex structures.

Measurement of the flow field induced by a spark plasma using particle image velocimetry

We investigate the local flow field induced by a spark plasma discharge in quiescent air under atmospheric conditions. Particle image velocimetry (PIV) is used to quantify the induced flow field between two conical-shaped electrodes for three different electrode gaps: 8 mm, 5 mm and 2 mm. The results show the existence of three distinct stages of flow. In the first stage of flow, distinct coherent structures are observed near the tips of the electrodes. In the second stage, ambient fluid is entrained along the electrodes to produce axial jets in the electrode gap. The final flow stage is characterized by collision of the jets and decay of vorticity. The flow parameters are all scaled by the induced velocity behind the shock wave produced by the spark and the electrode gap distance. The scaling results in comparable magnitudes of velocity and vorticity induced in the 5 mm and 8 mm electrode gaps with the onset of each of the flow stages occurring at approximately the same time scale. The magnitude of axial velocity dominates the latter two stages of the flow. Significant correlation is found between circulation and entrainment calculated for the 5 mm and 8 mm electrode gaps at different time steps, where the decay rates of circulation and that of entrainment are found to be $$\sim 1/(t/{\tau )^{0.75}}$$ and $$\sim 1/(t/{\tau) ^{0.88}}$$ , respectively. The stages of flow development for different electrode gaps at times > 100 µs after the discharge are discussed comprehensively and the choice of scaling based on energy deposited in the electrode gap and gap distance is found to permit direct comparison of the two electrode gaps.

The Effects of Free Vortex Decay in Quasi-Classical and Ultra-Quantum Turbulence

Free decay of homogeneous vortex tangle in superfluid has been studied for ultra-quantum and quasi-classical regimes at zero temperature limit. It is found that the decay process is associated with heating by means of phonon generation into the system, even at such a zero temperature limit. An explicit expression for the time evolution of temperature due to the heating has been derived. Such heating affects the motion of vortex strings by (a) decreasing their cyclotron frequencies and (b) shortening their length. This length shortening is a secondary decay process initiated by the primary free decay of vortex tangles. The effect of quasiparticles (phonons) on the wave collapse and energy dissipation of the turbulent states has also been studied through the modulation theory.

Volumetric Velocimetry Measurements of Film Cooling Jets

This paper presents volumetric velocimetry (VV) measurements for a jet in crossflow that is representative of film cooling. VV employs particle tracking to nonintrusively extract all three components of velocity in a three-dimensional volume. This is its first use in a film-cooling context. The primary research objective was to develop this novel measurement technique for turbomachinery applications, while collecting a high-quality data set that can improve the understanding of the flow structure of the cooling jet. A new facility was designed and manufactured for this study with emphasis on optical access and controlled boundary conditions. For a range of momentum flux ratios from 0.65 to 6.5, the measurements clearly show the penetration of the cooling jet into the freestream, the formation of kidney-shaped vortices, and entrainment of main flow into the jet. The results are compared to published studies using different experimental techniques, with good agreement. Further quantitative analysis of the location of the kidney vortices demonstrates their lift off from the wall and increasing lateral separation with increasing momentum flux ratio. The lateral divergence correlates very well with the self-induced velocity created by the wall–vortex interaction. Circulation measurements quantify the initial roll up and decay of the kidney vortices and show that the point of maximum circulation moves downstream with increasing momentum flux ratio. The potential for nonintrusive VV measurements in turbomachinery flow has been clearly demonstrated.

Reanalysis intercomparisons of stratospheric polar processing diagnostics.

We compare herein polar processing diagnostics derived from the four most recent full-input reanalysis datasets: the National Centers for Environmental Prediction Climate Forecast System Reanalysis / Climate Forecast System, version 2 (CFSR/CFSv2), the European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-Interim), the Japanese Meteorological Agency's Japanese 55-year Reanalysis (JRA-55), and the National Aeronautics and Space Administration's Modern Era Retrospective-analysis for Research and Applications version 2 (MERRA-2). We focus on diagnostics based on temperatures and potential vorticity (PV) in the lower to middle stratosphere that are related to formation of polar stratospheric clouds (PSCs), chlorine activation, and the strength, size, and longevity of the stratospheric polar vortex. Polar minimum temperatures (Tmin) and the area of regions having temperatures below PSC formation thresholds (APSC) show large persistent differences between the reanalyses, especially in the southern hemisphere (SH), for years prior to 1999. Average absolute differences of the reanalyses from the reanalysis ensemble mean (REM) in Tmin are as large as 3 K at some levels in the SH (1.5 K in the NH), and absolute differences of reanalysis APSC from the REM up to 1.5% of a hemisphere (0.75% of a hemisphere in the NH). After 1999, the reanalyses converge toward better agreement in both hemispheres, dramatically so in the SH: Average Tmin differences from the REM are generally less than 1 K in both hemispheres, and average APSC differences less than 0.3% of a hemisphere. The comparisons of diagnostics based on isentropic PV for assessing polar vortex characteristics, including maximum PV gradients (MPVG) and the area of the vortex in sunlight (or sunlit vortex area, SVA), show more complex behavior: SH MPVG showed convergence toward better agreement with the REM after 1999, while NH MPVG differences remained largely constant over time; differences in SVA remained relatively constant in both hemispheres. While the average differences from the REM are generally small for these vortex diagnostics, understanding such differences among the reanalyses is complicated by the need to use different methods to obtain vertically-resolved PV for the different reanalyses. We also evaluated other winter season summary diagnostics, including the winter mean volume of air below PSC thresholds, and vortex decay dates. For the volume of air below PSC thresholds, the reanalyses generally agree best in the SH, where relatively small interannual variability has led to many winter seasons with similar polar processing potential and duration, and thus low sensitivity to differences in meteorological conditions among the reanalyses. In contrast, the large interannual variability of NH winters has given rise to many seasons with marginal conditions that are more sensitive to reanalysis differences. For vortex decay dates, larger differences are seen in the SH than in the NH; in general the differences in decay dates among the reanalyses follow from persistent differences in their vortex areas. Our results indicate that the transition from the reanalyses assimilating Tiros Operational Vertical Sounder (TOVS) data to Advanced TOVS and other data around 1998 - 2000 resulted in a profound improvement in the agreement of the temperature diagnostics presented (especially in the SH) and to a lesser extent the agreement of the vortex diagnostics. We present several recommendations for using reanalyses in polar processing studies, particularly related to the sensitivity to changes in data inputs and assimilation. Because of these sensitivities, we urge great caution for studies aiming to assess trends derived from reanalysis temperatures. We also argue that one of the best ways to assess the sensitivity of scientific results on polar processing is to use multiple reanalysis datasets.

Analysis of the effect of vortex on the flow field of a cylindrical cyclone separator

This study presents a new method to analyze the vortex of cyclone separator by using the vortex identification of Q criterion. The Phase Doppler Particle Analyzer (PDPA) is used to measure the flow, and the numerical simulation is done by using the Reynolds stress model (RSM). In addition, a new conception of iso-vortex surface according to Q criterion is proposed for identifying the vortex structure. Since the model is validated by agreement between the numerical results and experimental data, and then is used to analyze the flow field. The results show that the tendency of the vortex structure is intuitive according to the new iso-vortex surface. Equivalent diameter of the iso-vortex surface is large in the upper region of the cylinder and decreases along the axis downward. The carrier energy of vortex decay gradually. In the process, vortex develops rapidly, even ruptures. Meanwhile, the vorticity magnitude has a sudden change near r/R = 0.93, and then vorticity magnitude rises up sharply. The vortex line of relative stable region is almost circular distribution, while the vortex line is complex at the upper region of cylinder, which has a hierarchical trend. The trend of the vortex center deviating from the geometric center firstly increases, reaches a peak value, and then reduces gradually. The axial position of peak value increases with the increase of velocity. Furthermore, the vortex structure can be appropriately adjusted to improve the flow instability, which is highly significant.

Investigation of Lamb–Oseen Vortex Evolution and Decay in Ground Proximity With Obstacle

The physical mechanism for the evolution and decay of Lamb–Oseen vortex pair in ground proximity with an obstacle has been investigated in detail by adopting the large eddy simulation (LES). In the present research, we mainly focus on the vortex evolution and decay mechanism in ground proximity with obstacle, so we chose one fixed height of the obstacle case (h0 = 0.5b0) to investigate, and the obstacle is placed transversally to the axis of the primary wake to be analyzed. The trajectories of the primary wake-vortex cores and the circulation profiles, as well as the distribution of the tangential velocity on different axial positions, have been specifically captured and analyzed. The “strake,” “claw,” and “ivory” vortices have been newly found and defined at the initial evolution stage, and they subsequently begin to harshly wind and rotate with the primary vortex. A flow structure with double helix conical shapes of the primary vortex has been found in the obstacle case. The pressure waves along the vortex axis have also been analyzed in detail. The wake-vortex on each side would be pulled in opposite axial directions and eventually pinched off at the upper surface of obstacle. Moreover, it has also been newly found that the trajectories of the wake-vortex in longitudinal directions at different axial distances away from the obstacle will experience two kinds of motion: only descending and rebounding after descending. Results obtained in this study provide a better understanding of mechanisms for the interaction of wake-vortex and the obstacle.

On the evolution of vortices in massive protoplanetary discs

It is expected that a pressure bump can be formed at the inner edge of a dead-zone, and where vortices can develop through the Rossby Wave Instability (RWI). It has been suggested that self-gravity can significantly affect the evolution of such vortices. We present the results of 2D hydrodynamical simulations of the evolution of vortices forming at a pressure bump in self-gravitating discs with Toomre parameter in the range $4-30$. We consider isothermal plus non-isothermal disc models that employ either the classical $\beta$ prescription or a more realistic treatment for cooling. The main aim is to investigate whether the condensating effect of self-gravity can stabilize vortices in sufficiently massive discs. We confirm that in isothermal disc models with ${\cal Q} \gtrsim 15$, vortex decay occurs due to the vortex self-gravitational torque. For discs with $3\lesssim {\cal Q} \lesssim 7$, the vortex develops gravitational instabilities within its core and undergoes gravitational collapse, whereas more massive discs give rise to the formation of global eccentric modes. In non-isothermal discs with $\beta$ cooling, the vortex maintains a turbulent core prior to undergoing gravitational collapse for $\beta \lesssim 0.1$, whereas it decays if $\beta \ge 1$. In models that incorpore both self-gravity and a better treatment for cooling, however, a stable vortex is formed with aspect ratio $\chi \sim 3-4$. Our results indicate that self-gravity significantly impacts the evolution of vortices forming in protoplanetary discs, although the thermodynamical structure of the vortex is equally important for determining its long-term dynamics.

Evaluation of Tropical Cyclone Structure Forecasts in a High-Resolution Version of the Multiscale GFDL fvGFS Model

Abstract A nested version of the cubed-sphere finite-volume dynamical core (FV3) with GFS physics (fvGFS) is capable of tropical cyclone (TC) prediction across multiple space and time scales, from subseasonal prediction to high-resolution structure and intensity forecasting. Here, a version of fvGFS with 2-km resolution covering most of the North Atlantic is evaluated for its ability to simulate TC track, intensity, and finescale structure. TC structure is evaluated through a comparison of forecasts with three-dimensional Doppler radar from P-3 flights by NOAA’s Hurricane Research Division (HRD), and the structural metrics evaluated include the 2-km radius of maximum wind (RMW), slope of the RMW, depth of the TC vortex, and horizontal vortex decay rate. Seven TCs from the 2010–16 seasons are evaluated, including 10 separate model runs and 38 individual flights. The model had some success in producing rapid intensification (RI) forecasts for Earl, Edouard, and Matthew. The fvGFS model successfully predicts RMWs in the 25–50-km range but tends to have a small bias at very large radii and a large bias at very small radii. The wind peak also tends to be somewhat too sharp, and the vortex depth occasionally has a high bias, especially for storms that are observed to be shallow. Composite radial wind shows that the boundary layer tends to be too deep, although the outflow structure aloft is relatively consistent with observations. These results highlight the utility of the structural evaluation of TC forecasts and also show the promise of fvGFS for forecasting TCs.

Taylor-Green vortex simulation using CABARET scheme in a weakly compressible formulation.

In present paper we recall the canonical Taylor-Green vortex problem solved by in-house implementation of the novel CABARET numerical scheme in weakly compressible formulation. The simulations were carried out on the sequence of refined grids with [Formula: see text], [Formula: see text], [Formula: see text] cells at various Reynolds numbers corresponding to both laminar ([Formula: see text]) and turbulent ([Formula: see text]) vortex decay scenarios. The features of the numerical method are discussed in terms of the kinetic energy dissipation rate and integral enstrophy curves, temporal evolution of the spanwise vorticity, energy spectra and spatial correlation functions.

Optimized Time-Resolved Echo Particle Image Velocimetry- Particle Tracking Velocimetry Measurements Elucidate Blood Flow in Patients With Left Ventricular Thrombus.

Contrast ultrasound is a widely used clinical tool to obtain real-time qualitative blood flow assessments in the heart, liver, etc. Echocardiographic particle image velocimetry (echo-PIV) is a technique for obtaining quantitative velocity maps from contrast ultrasound images. However, unlike optical particle image velocimetry (PIV), routine echo images are prone to nonuniform spatiotemporal variations in tracer distribution, making analysis difficult for standard PIV algorithms. This study introduces optimized procedures that integrate image enhancement, PIV, and particle tracking velocimetry (PTV) to obtain reliable time-resolved two-dimensional (2D) velocity distributions. During initial PIV analysis, multiple results are obtained by varying processing parameters. Optimization involving outlier removal and smoothing is used to select the correct vector. These results are used in a multiparameter PTV procedure. To demonstrate their clinical value, the procedures are implemented to obtain velocity and vorticity distributions over multiple cardiac cycles using images acquired from four left ventricular thrombus (LVT) patients. Phase-averaged data elucidate flow structure evolution over the cycle and are used to calculate penetration depth and strength of left ventricular (LV) vortices, as well as apical velocity induced by them. The present data are consistent with previous time-averaged results for the minimum vortex penetration depth associated with LVT occurrence. However, due to decay and fragmentation of LV vortices, as they migrate away from the mitral annulus, in two cases with high penetration, there is still poor washing near the resolved clot throughout the cycle. Hence, direct examination of entire flow evolution may be useful for assessing risk of LVT relapse before prescribing anticoagulants.

A parallel stability analysis of a trailing vortex wake

Trailing vortices are generated in aeronautical and maritime applications and produce a variety of adverse effects that remain difficult to control. A stability analysis can direct flow control designers towards pertinent frequencies, wavelengths and locations that may lead to the excitation of instabilities, resulting in the eventual breakup of the vortex. Most models for trailing vortices, however, are far-field models, making implementation of the findings from stability analyses challenging. As such, we perform a stability analysis in the formative region where the numerically computed base flow contains both a two-dimensional wake and a tip vortex generated from a NACA0012 at a$5^{\circ }$angle of attack and a chord-based Reynolds number of$Re_{c}=1000$. The parallel temporal and spatial analyses show that at three chord lengths downstream of the trailing edge, seven unstable modes are present: three stemming from the temporal analysis and four arising in the spatial analysis. The three temporal instabilities are analogues to three unstable modes in the spatial analysis, with the wake instability dominating in both analyses. The helical mode localized to the vortex co-rotates with the base flow, which is converse with the counter-rotating$m=-1$instabilities of a Batchelor vortex model, which may be a result of the formative nature of the base-flow vortex. The fourth spatial mode is localized to the tip vortex region. The continuous part of the spectrum contains oscillatory and wavepacket solutions prompting the utilization of a wavepacket analysis to analyse the flow field and group velocity. The structure and details of the full bi-global spectrum will help navigate the design space of effective control strategies to hasten decay of persistent wingtip vortices.

Tunneling decay of self-gravitating vortices

We investigate tunneling decay of false vortices in the presence of gravity, in which vortices are trapped in the false vacuum of a theory of scalar electrodynamics in three dimensions. The core of the vortex contains magnetic flux in the true vacuum, while outside the vortex is the appropriate topologically nontrivial false vacuum. We numerically obtain vortex solutions which are classically stable; however, they could decay via tunneling. To show this phenomenon, we construct the proper junction conditions in curved spacetime. We find that the tunneling exponent for the vortices is half that for Coleman-de Luccia bubbles and discuss possible future applications.

Comparison and validation of wake vortex characteristics collected at different airports by different scanning lidar sensors

Today, the demand for increasing airport capacity is high, in particular for increasing runway throughput from an ATM perspective. Runway capacity is often directly linked with the minima longitudinal separation between aircraft on approach phase or between aircraft on departure. The separation minima are based on surveillance capabilities and on wake turbulence (WT) in order to mitigate respectively collision risk and WT-induced accidents, therefore WT hazard becomes a major concern for ATM. For ten years, many research LIDAR systems have been used for better understanding wake vortices behaviors in the operational environment within large range of wind and turbulence conditions. All these studies[1][2] helped to design new concepts of wake separations between aircrafts thanks to the proven capabilities of LIDAR systems to assess the risks of wake vortex (WV) encounters through the circulation retrievals. The re-categorization project, called RECAT [8], has been launched by a joint EUROCONTROL – FAA initiative in order to renew and optimize the out-of-date currently applied ICAO regulations on distance separation. Nowadays, the first phase of regional RECAT projects, which consists in defining new distance separation matrices composed of six/seven static aircraft categories instead of three, entered the operational phase and is deployed in several airports in United States and Europe. In addition, other concepts like Time-Based Separation have also been studied and deployed in London Heathrow. The airports where these solutions have been deployed obtained significant benefits as increased runway throughput and improved resilience to disruptions. For implementing such new WT solutions at an airport, a local safety assessment before the implementation and a risk monitoring after are usually needed. Before implementation, it may be required to determine for the targeted airport the relative variations of risk of wake vortex encounters, given the local ATM rules, the traffic mix, the weather conditions and their impact on the wake vortex decay. After implementation, the risk monitoring might perform in-depth analysis of wake vortex encounter reported by pilots. For all the mentioned steps, the use of scanning Doppler LIDARs is the only experimental sensor capable of measuring the localization and the circulation of the wake vortices and to provide ground truth wake vortex measurements. Next generation operational LIDARs need to be developed to address in a cost effective way these operational needs. Furthermore, a specific configuration and methodology need to be developed to ensure the accuracy of the wake vortex data. Such a LIDAR based wake vortex solution has been tested at Paris Charles De Gaulle which implemented the RECAT-EU wake separation scheme. The wake vortex circulation, initial spacing and decay measured have been compared to the data collected in London Heathrow by a different LIDAR sensor. The results indicated that the initial circulation, the time to demise, the decay curve evolution and the vortex spacing are very coherent between the two databases.

Application of the Haar Wavelet to the Analysis of Plasma and Atmospheric Fluctuations

The parameters of turbulence measured by means of a Doppler reflectometer at the plasma periphery in an L-2M stellarator and in atmospheric vortices (typhoons and tornadoes) are investigated using the wavelet methods with involvement of the Haar function. The periods of time taken for the transition (a bound of parameters) to occur in the L-2M stellarator plasma and in atmospheric processes are estimated. It is shown that high-and low-frequency oscillations of certain parameters, in particular, pressure, that occur in atmospheric vortices decay or increase at different moments of time, whereas the density fluctuation amplitudes that occur in plasma at different frequencies vary in a synchronous manner.

Tunneling decay of false vortices with gravitation

We study the effect of vortices on the tunneling decay of a symmetry-breaking false vacuum in three spacetime dimensions with gravity. The scenario considered is one in which the initial state, rather than being the homogeneous false vacuum, contains false vortices. The question addressed is whether, and, if so, under which circumstances, the presence of vortices has a significant catalyzing effect on vacuum decay. After studying the existence and properties of vortices, we study their decay rate through quantum tunneling using a variety of techniques. In particular, for so-called thin-wall vortices we devise a one-parameter family of configurations allowing a quantum-mechanical calculation of tunneling. Also for thin-wall vortices, we employ the Israel junction conditions between the interior and exterior spacetimes. Matching these two spacetimes reveals a decay channel which results in an unstable, expanding vortex. We find that the tunneling exponent for vortices, which is the dominant factor in the decay rate, is half that for Coleman-de Luccia bubbles. This implies that vortices are short-lived, making them cosmologically significant even for low vortex densities. In the limit of the vanishing gravitational constant we smoothly recover our earlier results for the decay of the false vortex in a model without gravity.

The effect of gusts on aircraft wake vortices

PurposeThis study aims to investigate the effect of gusts on aircraft wake vortices. Aircraft wake vortices present a potential risk to following aircraft, particularly during final approach and landing, as wake vortices may remain in the flight corridor for a long time. Wind and turbulence are key factors that influence the wake vortex evolution and the wake vortex generation in the aircraft. Flying through a gust influences the wake vortex roll-up process and its evolution. Note that vertical and lateral gusts may affect counter-rotating wake vortices differently. Both vortices influence each other by inducing a downward velocity. Disturbances may therefore lead to local vortex tilting and later to a complex three-dimensional deformation. This work uses two different hybrid Reynolds-averaged Navier–Stokes/large-eddy simulation (RANS-LES) approaches to investigate the effect of gusts on wake vortex evolution. In a one-way coupling, a pre-calculated RANS velocity field of the aircraft’s near-field is being swept through an LES domain. The effect of a sine gust on the turbulent wake is modeled by manipulating the RANS-field accordingly. As a more sophisticated approach, the concept of a two-way coupling is being presented. Here an LES solver is bi-directionally coupled with an unsteady RANS (URANS) solver, exchanging values at every physical time step of the simulation.Design/methodology/approachA one-way coupling approach of the LES code MGLET and the RANS code TAU is presented to simulate the gust effect on aircraft wake vortices. Additionally, the concept of the two-way coupling of these two codes incorporating a coupling module.FindingsThe gust effect of wake vortices subjected to a crosswind can be simulated. The vortex physics is analyzed. Unexpected behavior like fast upwind vortex decay is revealed.Practical implicationsThe understanding of the aircraft wake vortex physics during landing provides valuable information for wake vortex advisory systems.Originality/valueThe effect of gust on wake vortices during and after landing has not been studied so far. The hybrid one-way coupling approach, as well as the concept of the two-way coupling, are relatively new.

Characteristics and evolution of an Agulhas ring

AbstractA South Atlantic ring is studied through remote sensing altimetry, hydrographic stations, and drifters' trajectories. The ring's core was characterized by warmer and saltier Indian Ocean waters. At the time of the cruise, the ring's signature extended radially out to 124 km and vertically down to 2000 m, and its core absolute dynamic topography (ADT) exceeded the surrounding Atlantic Ocean waters in 0.4 m. The geostrophic velocities were anticyclonic with maximum speeds about 35 cm s−1 at 100 m and reaching negligible values near 4500 m. The rotational transport inside the ring was 33 Sv in the thermocline and intermediate layers. The drifters' data distinguish a 30‐km core revolving as a solid body with periodicity near 5 days and a transitional band that revolves with constant tangential velocity, resembling a Rankine vortex. The ADT data identify the ring's track, showing that it was shed by the Agulhas Current retroflection in November 2009 and propagated northwest rapidly during the first 2 months (mean speed of about 10 cm s−1) but slowed down substantially (3–4 cm s−1) between March and July 2010, when it was last detected. The altimetry data also outlines the evolution of the ring's core ADT, radius, vorticity, and, through a simple calibration with the cruise data, rotational transport. In particular, the ring surface and vertical‐mean vorticity decay with time scales of 373 and 230 days, respectively, indicating that most of the property anomalies contained by the ring are diffused out to the subtropical gyre before it reaches the western boundary current system.

Vinen turbulence via the decay of multicharged vortices in trapped atomic Bose-Einstein condensates

We investigate a procedure to generate turbulence in a trapped Bose-Einstein condensate which takes advantage of the decay of multicharged vortices to reduce surface oscillations. We show that the resulting singly charged vortices twist around each other, intertwined in the shape of helical Kelvin waves, which collide and undergo vortex reconnections, creating a disordered vortex state. By examining the velocity statistics, the energy spectrum, the correlation functions, and the temporal decay and comparing these properties with the properties of classical turbulence and observations in superfluid helium, we conclude that this disordered vortex state can be identified with the Vinen regime of turbulence which has been discovered in the context of superfluid helium.

Quasi-ideal dynamics of vortex solitons embedded in flattop nonlinear Bessel beams.

The applications of vortex solitons are severely limited by the diffraction and self-defocusing spreading of the background beam where they are nested. Nonlinear Bessel beams in self-defocusing media are nondiffracting, flattop beams where the nested vortex solitons can survive for propagation distances that are one order of magnitude larger than in the Gaussian or super-Gaussian beams. The dynamics of the vortex solitons is studied numerically and found to approach that in the ideal, uniform background, preventing vortex spiraling and decay, which eases vortex steering for applications.