This paper examines a model that combines vortex generators and leading-edge tubercles for controlling the laminar separation bubble(LSB)over an airfoil at low Reynolds numbers(Re).This new concept of passive flow con...This paper examines a model that combines vortex generators and leading-edge tubercles for controlling the laminar separation bubble(LSB)over an airfoil at low Reynolds numbers(Re).This new concept of passive flow control technique utilizing a tubercle and vortex generator(VG)close to the leading edge was analyzed numerically for a NACA0015 airfoil.In this study,the Shear Stress Transport(SST)turbulence model was employed in the numerical modelling.Numerical modelling was completed using the ANSYS-Fluent 18.2 solver.Analyses were conducted to investigate the flow pattern and understand the underlying LSB control phenomena that enabled the new passive flow control method to provide this significant performance benefit.The findings indicated that the new concept of passive flow control technique suppressed the formation of an LSB at the suction surface of the NACA0015 airfoil,resulting in a higher lift coefficient and improved aerodynamic performance.Improvements in LSB dynamics and aerodynamic performance through the passive flow control method lead to increased energy output and enhanced stability.展开更多
Typhoon Bebinca in 2024 experienced a nearshore outbreak(a rapid intensification(RI)near the coast),making accurate forecasting of unpredictable tracks and intensities highly challenging.The AI model is superior to th...Typhoon Bebinca in 2024 experienced a nearshore outbreak(a rapid intensification(RI)near the coast),making accurate forecasting of unpredictable tracks and intensities highly challenging.The AI model is superior to the numerical model for typhoon track prediction but performs worse for intensity forecasting.Vortex initialization is an effective approach to further improve numerical prediction via cycle assimilation,accounting for multiple relocating TC centers and adjusting the typhoon initial structure.In addition,by integrating numerical runs with an AI weather model through real-time dynamic weight correction of the forecast,the predictive skill is further improved.For example,it can reduce the deviation of 72-h track forecasting by 25%compared with the numerical model and decrease the intensity deviation by 2%and 56%relative to the numerical run and AI forecasts,respectively.On the basis of the best-performing forecasting,the inner-core convective burst(CB)characteristics are illuminated.The attributions of the nearshore outbreak and RI of Typhoon Bebinca are examined.From the viewpoint of bottom-up convection growth,the CB is associated with the energy supply from the high-boundarylayer CAPE,the following upward-developing secondary circulation,and accompanying latent heat release of hydrometeors.The contracted radius of maximum winds(RMW)and increased inertial stability within the inner core region effectively prevent the escape of the high-energy atmosphere and favor rapid intensification and maintenance of the offshore burst of a typhoon.The intensifying secondary circulation further promotes the primary circulation of the TC and RI processes through the gradient wind balance.展开更多
This paper examines the connection between photonic band-gap formation in two types of two-dimensional photonic crystals and the emergence of reverse electromagnetic energy flows generated by linearly polarized plane ...This paper examines the connection between photonic band-gap formation in two types of two-dimensional photonic crystals and the emergence of reverse electromagnetic energy flows generated by linearly polarized plane waves incident on a photonic-crystal slab.We show that these reverse energy flows,observed in both transmitted and reflected fields,originate from vortex structures in the Poynting vector.The resulting energy-flow patterns exhibit striking analogies to vortex formation in fluid motion past obstacles.The geometry and dynamics of the Poynting-vector vortices determine whether the incident electromagnetic energy is impeded,leading to the formation of photonic band gaps,or instead guided through the structure,enabling transmission.展开更多
The Northeast China Cold Vortex(NCCV)is a common cut-off low-pressure system in Northeast China,frequently causing localized heavy rainfall,strong winds,and thunderstorms during the early summer.In this study,the clea...The Northeast China Cold Vortex(NCCV)is a common cut-off low-pressure system in Northeast China,frequently causing localized heavy rainfall,strong winds,and thunderstorms during the early summer.In this study,the clear-sky radiance of 48 longwave channels from the FY-4B Geostationary Interferometric Infrared Sounder(GIIRS)is assimilated into the China Meteorological Administration mesoscale model(CMA-MESO)to evaluate its impact on NCCV development and its effects on rainfall forecasting.The results show that after assimilating the GIIRS radiance data,the warm center at 200 hPa and the cold center at 850 hPa of the NCCV are strengthened,and the dry intrusion at 850 hPa becomes more pronounced.This leads to a stronger NCCV intensity in the following 24 hours and brings the precipitation intensity and area closer to the observation,resulting in significant improvements compared to the experiments that do not assimilate GIIRS radiance data.Furthermore,it is found that the enhancement of the precipitation forecast is associated with the strengthening of cold air in the middle and lower troposphere,which intensifies the uplift of the warm,moist airflow.These results highlight the potential value of GIIRS data assimilation in enhancing early warnings and forecasts of extreme weather events influenced by the NCCV.展开更多
We study Onsager vortex clustered states in a shell-shaped superfluid containing a large number of quantum vortices.In the incompressible limit and at low temperatures,the relevant problem can be boiled down to the st...We study Onsager vortex clustered states in a shell-shaped superfluid containing a large number of quantum vortices.In the incompressible limit and at low temperatures,the relevant problem can be boiled down to the statistical mechanics of neutral point vortices confined on a sphere.We analyze rotation-free vortex-clustered states within the mean-field theory in the microcanonical ensemble.We find that the sandwich state,which involves the separating of vortices with opposite circulation and the clustering of vortices with the same circulation around the poles and the equator,is the maximum entropy vortex distribution,subject to a zero angular momentum constraint.The dipole moment vanishes for the sandwich state and the quadrupole tensor serves as an order parameter to characterize the vortex cluster structure.For a given finite angular momentum,the equilibrium vortex distribution forms a dipole structure,i.e.,vortices with opposite sign are separated and accumulate around the south and north poles,respectively.The conditions for the onset of clustering and the exponents associated with the quadrupole moment and the dipole moment as functions of energy are obtained within the mean field theory.At large energies,we obtain asymptotically exact vortex density distributions using the stereographic projection method,yielding the parameter bounds for the vortex clustered states.The analytical predictions are in excellent agreement with microcanonical Monte Carlo simulations.展开更多
By introducing noncanonical vortex pairs to partially coherent beams, spatial correlation singularity (SCS) and orbital angular momenta (OAM) of the resulting beams are studied using the Fraunhofer diffraction integra...By introducing noncanonical vortex pairs to partially coherent beams, spatial correlation singularity (SCS) and orbital angular momenta (OAM) of the resulting beams are studied using the Fraunhofer diffraction integral. The effect of noncanonical strength, off-axis distance and vortex sign on spatial correlation singularities in far field is stressed. Furthermore, far-field OAM spectra and densities are also investigated, and the OAM detection and crosstalk probabilities are discussed. The results show that the number of dislocations of SCS always equals the sum of absolute values of topological charges for canonical or noncanonical vortex pairs. Although the sum of the product of each OAM mode and its power weight equals the algebraic sum of topological charges for canonical vortex pairs, the relationship no longer holds in the noncanonical case except for opposite-charge vortex pairs. The changes of off-axis distance, noncanonical strength or coherence length can lead to a more dominant power in adjacent mode than that in center detection mode, which also indicates that crosstalk probabilities of adjacent modes exceed the center detection probability. This work may provide potential applications in OAM-based optical communication, imaging, sensing and computing.展开更多
This study investigates extreme rainfall episodes along the eastern foothills of the Taihang Mountains in North China from 30 July to 1 August 2023.It focuses on two types of extreme hourly rainfall rates(HRRs),i.e.,t...This study investigates extreme rainfall episodes along the eastern foothills of the Taihang Mountains in North China from 30 July to 1 August 2023.It focuses on two types of extreme hourly rainfall rates(HRRs),i.e.,the maximum regionalaverage HRR and site-observed HRR,which exhibited sequential development over southern,middle,and northern key regions.These rainfall extremes occurred in an environment where a high-pressure barrier over North China prevented the intrusion of cold air masses from the north while a northward-moving typhoon remnant vortex and its associated low-level jet(LLJ)transported warm and moist airflow from the south.Two distinct echo evolution modes and convection initiation mechanisms are identified for the two types of extreme HRRs.The maximum regional-average HRR occurred when the LLJ arrived to the east of the key regions,while the maximum site-observed HRR occurred when the warmer vortex center influenced the regions.Taking the northern key region as a representation,at the time of the maximum regional-average HRR,slantwise ascent of the airflow along a warm-frontal-like boundary released energy related to symmetrical instability,resulting in stratiform rainfall with weak convective cores.The transport of locally initiated convection over the eastern plain region,where the atmospheric stratification was more potentially unstable,also significantly contributed.When the maximum site-observed HRR occurred,the terrain lifting of warm and moist southeast airflow led to intense convection over the mountain foothills.Overall,the passage of the warm-core typhoon remnant vortex and interaction with Taihang Mountains determined the timing and location of extreme HRRs across the key regions.展开更多
The free-surface vortex is a rotational flow phenomenon characterized by two-phase coupling,formed by the rupture of surface fluid in the final stage of discharge.It is a significant concept with broad applications in...The free-surface vortex is a rotational flow phenomenon characterized by two-phase coupling,formed by the rupture of surface fluid in the final stage of discharge.It is a significant concept with broad applications in engineering fields like metallurgy and hydraulics.The basic concepts and characteristics of free-surface vortices were introduced,and their hazards in various fields were discussed.The development of theoretical and numerical models over recent decades was reviewed,and the factors affecting vortex formation and existing suppression methods were outlined.Finally,the key challenges and focus areas on the study of free-surface vortex were summarized.With the ongoing advancements in computational fluid dynamics and experimental technology,research on free-surface vortices will become more in depth and precise.Additionally,interdisciplinary cooperation and technological innovation are expected to achieve precise control and optimal design of free-surface vortices,offering more efficient and sustainable solutions for metallurgy and related engineering fields.展开更多
We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW...We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW structure interacts with a weak probe laser field,a spatially independent 2D standing-wave(SW)field,and a Laguerre–Gaussian(LG)vortex field,respectively.The results indicate that the diffraction patterns are highly sensitive to amplitude modulation and phase modulation.Because of the existence of vortex light,it is possible to realize asymmetric high-order diffraction in the SQW structure,and then a 2D asymmetric grating is established.By adjusting the detunings of the probe field,vortex field,and SW field,as well as the interaction length,diffraction intensity,and direction of the 2D asymmetric electromagnetically induced grating(EIG)can be controlled effectively.In addition,the number of orbital angular momenta(OAM)and beam waist parameter can be used to modulate the diffraction intensity and energy transfer of the probe light in different regions.High-order diffraction intensity is enhanced and high-efficiency 2D asymmetric diffraction grating with different diffraction patterns is obtained in the scheme.Such 2D asymmetric diffraction grating may be beneficial to the research of optical communication and innovative semiconductor quantum devices.展开更多
Pairs of entangled vortex photons can promise new prospects of application in quantum computing and cryptography.We investigate the possibility of generating such states via two-level atom emission induced by a single...Pairs of entangled vortex photons can promise new prospects of application in quantum computing and cryptography.We investigate the possibility of generating such states via two-level atom emission induced by a single photon wave packet with a definite total angular momentum(TAM).The entangled pair produced in this process possesses well-defined mean TAM with the TAM variation being much smaller than h.On top of that,the variation exponentially decreases with the increase in TAM of the incident photon.Our model allows one to track the time evolution of the state of the entangled pair.An experimentally feasible scenario is assumed,in which the incident photon interacts with a spatially confined atomic target.We conclude that induced emission can be used as a source of entangled vortex photons with applications in atomic physics experiments,quantum optics,and quantum information sciences.展开更多
To delay the vortex breakdown position of the slender delta wing,this study innovativelyproposes the application of control near the Leading-Edge Vortex(LEV)core sweeping path,whichis called Coupled Core Rotation Dual...To delay the vortex breakdown position of the slender delta wing,this study innovativelyproposes the application of control near the Leading-Edge Vortex(LEV)core sweeping path,whichis called Coupled Core Rotation Dual Synthetic Jets(CCR-DSJ)control.The results show that thevortex breakdown points at each angle of attack are moved backward after control,and the max-imum delayed displacement is 32.4%of the root chord at 30°.Besides,there is a linear relationshipbetween the breakdown position and the angle of attack after control,indicating that CCR-DSJcontrol has a significant effect on the pressure gradient of the vortex axis.Furthermore,the lift coef-ficient C_(L)is enhanced after control,with a maximum CLincrement of 0.078 at 27°,and an effectiveincrement interval of[25°,32°].This interval is different from most previous studies,which isdirectly related to the position of the actuators.According to the lift change mechanism,the anglesof attack are divided into three stages:Stage 1(a=15°–25°),Stage 2(a=25°–32°),and Stage 3(a=32°–40°).In conclusion,CCR-DSJ control can significantly change the pressure distribution,thereby offering promising prospects for the flight stage of the slender delta wing.展开更多
The vortex dynamics after the initial ring dark solitons in two-component ultracold Rydberg atomic systems have been investigated.The two parameters characterizing the Rydberg long-range interaction—namely,the Rydber...The vortex dynamics after the initial ring dark solitons in two-component ultracold Rydberg atomic systems have been investigated.The two parameters characterizing the Rydberg long-range interaction—namely,the Rydberg strength and the blockade radius—along with the initial depth,are identified as the main factors that affect the vortex dynamics.In the absence of Rydberg soft-core potential and spin-orbit coupling,the late vortex dipoles move along x-or y-axis first.However,this work demonstrates that,with certain Rydberg strength and blockade radius,the late vortex dipoles move towards the edge at an oblique angle to the coordinate axes,and it reveals that the Rydberg nonlocal nonlinear interaction shortens the lifetime of late vortices.When the intra-component and inter-component Rydberg strengths are different,the backgrounds of the two components gradually complement each other,and the lifetime of late vortices is significantly shortened.The presented results show that the Rydberg dressing breaks the rule that the initial average depth determines the number and paths of vortices.The motion features of vortex dipoles in the ultracold Rydberg atomic system have been ascertained,and their directions of movement can be predicted to some degree based on the rotation directions and initial positions of the vortices.展开更多
Chirality,a common phenomenon in nature,appears in structures ranging from galaxies and condensed matter to atomic nuclei.There is a persistent demand for new,high-precision methods to detect chiral structures,particu...Chirality,a common phenomenon in nature,appears in structures ranging from galaxies and condensed matter to atomic nuclei.There is a persistent demand for new,high-precision methods to detect chiral structures,particularly at the microscale.Here,we propose a novel method,vortex Mössbauer spectroscopy,for probing chiral structures.By leveraging the orbital angular momentum carried by vortex beams,this approach achieves high precision in detecting chiral structures at scales ranging from nanometers to hundreds of nanometers.Our simulation shows the ratio of characteristic lines in the Mössbauer spectra of ^(57)Fe under vortex beams exhibits differences of up to four orders of magnitude for atomic structures with different arrangements.Additionally,simulations reveal the response of ^(229m)Th chiral structures to vortex beams with opposite angular momenta differs by approximately 49-fold.These significant spectral variations indicate that this new vortex Mössbauer probe holds great potential for investigating the microscopic chiral structures and interactions of matter.展开更多
Regional turbofan aircraft,which are used for medium-short distances,have a heightened risk of high-altitude Wake Vortices(VV)because of their tail-mounted engines and high horizontal tail configurations.For some regi...Regional turbofan aircraft,which are used for medium-short distances,have a heightened risk of high-altitude Wake Vortices(VV)because of their tail-mounted engines and high horizontal tail configurations.For some regional medium-short-range turbofan aircraft,this threat is higher than that for conventionally designed aircraft.To analyze the flight safety of turbofan aircraft during cruise,this study developed a model to assess wake vortex encounters based on evolutionary high-altitude wake flow patterns.First,the high-altitude wake vortex aircraft dissipation patterns were analyzed by combining Quick Access Recorder(QAR)flight data with the wake vortex evolution model.Then,to consider the uniqueness of the medium-short-range turbofan aircraft,the severity of the wake vortex encounters was simulated using an induced roll moment coefficient.The proposed high-altitude wake vortex encounter model was able to identify and assess the highaltitude wake vortex changes,the bearing moments at different altitudes,and the atmospheric pressure conditions.Using the latest wake separation standards from the International Civil Aviation Organization(ICAO),acceptable safety wake intervals for follower aircraft in different scenarios were determined for the safety assessment.The results indicate that compared to mid and low altitudes,the high-altitude aircraft wake vortex dissipation rate is faster,the ultimate bearing moment is weaker,and the roll moment coefficient is higher,which confirm that there is elevated wake vortex encounter severity for regional turbofan aircraft.As safety is found to deteriorate when encountering wake vortices at altitudes higher than 8 km,new medium-short-range turbofan regional aircraft require higher safety margins than the latest wake separation standards.展开更多
When a perpendicular magnetic field penetrates a thin slab of a type-Ⅱ superconductor it produces vortices,with one vortex per flux quantum,h/2e.The vortices interact repulsively and form an ordered array(Abrikosov l...When a perpendicular magnetic field penetrates a thin slab of a type-Ⅱ superconductor it produces vortices,with one vortex per flux quantum,h/2e.The vortices interact repulsively and form an ordered array(Abrikosov lattice)in clean systems,while strong disorder changes the lattice into a vortex glass.The collective vortex dynamics is extremely vulnerable to external perturbations.Consequently,although of great importance,experimental observation is limited.Here we investigate type-Ⅱ superconducting films(PdBi_(2)and NbSe_(2))with surface acoustic waves(SAWs)at mK temperature.When sweeping the magnetic field at an extremely slow rate,we observe a series of spikes in the attenuation and velocity of the SAW,on average separated in field by approximately Hc1.We propose the following scenario:The vortex-free region at the edges of the film produces an edge barrier across which the vortices can enter or leave.When the applied field changes,the induced supercurrents flowing along this edge region lowers this barrier until there is an instability.At that point,vortices avalanche into(or out of)the bulk and change the vortex crystal,suggested by the sharp jump in each such spike.The vortices then gradually relax to a new stable pinned configuration,leading to a~30 s relaxation after the jump.Our observation enriches the limited experimental evidence on the important topic of real-time vortex dynamics in superconductors.展开更多
The present study investigates the non-isothermal flow and energy distribution through a loosely bent rectangular duct using a spectral-based numerical approach over a wide range of the Dean number 0<Dn≤3000.Unlik...The present study investigates the non-isothermal flow and energy distribution through a loosely bent rectangular duct using a spectral-based numerical approach over a wide range of the Dean number 0<Dn≤3000.Unlike previous research,this work offers novel insights by conducting a grid-point-specific velocity analysis and identifying new bifurcation structures.The study reveals how centrifugal and buoyancy forces interact to produce steady,periodic,and chaotic flow regimes significantly influencing heat transfer performance.The Newton-Raphson method is employed to explore four asymmetric steady branches,with vortex solutions ranging from 2-to 12 vortices.Unsteady flow characteristics are analyzed exquisitely by performing time-advancement of the solutions and the flow regimes are shown as a percentage of total flow with longitudinal vortex generation.Axial flow,secondary flow,and temperature profiles have been depicted in accordance with Dn to wander the flow pattern,and it is predicted that the time-dependent flow(TDF)consists of asymmetric 2-to 10-vortex solutions.The significant findings of this study include the axial displacement of the circulations due to the influence of the time-varying temperature dispersal applied along the wall.Chaotic flows,which dominate the higher Dean number range,are shown to enhance heat convection due to increased fluid mixing.A detailed comparison with prior research demonstrates the advantages of this approach,particularly in capturing complex non-linear behaviors.The findings of this study provide practical guidelines for optimizing duct designs to maximize heat transfer and suggest future research directions,such as using nanofluids or studying Magneto-hydrodynamics in the same configuration.展开更多
Orbital angular momentum(OAM)can achieve multifold increase of spectrum efficiency,but the hollow divergence characteristic and Line-of-Sight(LoS)path requirement impose the crucial challenges for vortex wave communic...Orbital angular momentum(OAM)can achieve multifold increase of spectrum efficiency,but the hollow divergence characteristic and Line-of-Sight(LoS)path requirement impose the crucial challenges for vortex wave communications.For air-to-ground vortex wave communications,where there exists the LoS path,this paper proposes a multi-user cooperative receive(MUCR)scheme to break through the communication distance limitation caused by the characteristic of vortex wave hollow divergence.In particular,we derive the optimal radial position corresponding to the maximum intensity,which is used to adjust the waist radius.Based on the waist radius and energy ring,the cooperative ground users having the minimum angular square difference are selected.Also,the signal compensation scheme is proposed to decompose OAM signals in air-to-ground vortex wave communications.Simulation results are presented to verify the superiority of our proposed MUCR scheme.展开更多
We propose a theoretical framework,based on the two-component Gross-Pitaevskii equation(GPE),for the investigation of vortex solitons(VSs)in hybrid atomic-molecular Bose-Einstein condensates under the action of the st...We propose a theoretical framework,based on the two-component Gross-Pitaevskii equation(GPE),for the investigation of vortex solitons(VSs)in hybrid atomic-molecular Bose-Einstein condensates under the action of the stimulated Raman-induced photoassociation and square-optical-lattice potential.Stationary solutions of the coupled GPE system are obtained by means of the imaginary-time integration,while the temporal dynamics are simulated using the fourth-order Runge-Kutta algorithm.The analysis reveals stable rhombus-shaped VS shapes with topological charges m=1 and 2 of the atomic component.The stability domains and spatial structure of these VSs are governed by three key parameters:the parametric-coupling strength(χ),atomicmolecular interaction strength(g_(12)),and the optical-lattice potential depth(V_(0)).By varyingχand g_(12),we demonstrate a structural transition where four-core rhombus-shaped VSs evolve into eight-core square-shaped modes,highlighting the nontrivial nonlinear dynamics of the system.This work establishes a connection between interactions of cold atoms and topologically structured matter waves in hybrid quantum systems.展开更多
A cylindrical chamber with a rotating bottom holds significant potential for application in cell culture bioreactors due to its ability to generate more stable swirling flows.In order to control vortex breakdown withi...A cylindrical chamber with a rotating bottom holds significant potential for application in cell culture bioreactors due to its ability to generate more stable swirling flows.In order to control vortex breakdown within the chamber,this study first establishes a computational fluid dynamics simulation coupled with the level set method.Verified by experimental results in literature,this method accurately simulates the position and shape of vortex breakdown,and also predicts the critical Reynolds numbers for the appearance and detachment of vortex breakdown bubbles from the center.Additionally,it precisely captures the gas-liquid interface and depicts the vortex breakdown phenomenon in the air above the liquid for the first time.Finally,it predicts the impact of physical property of gas-liquid systems on vortex breakdown in response to significant changes in viscosity of microbial process systems.展开更多
Acoustic wave isolation and noise reduction are significant challenges in the fields of physics and various applications.Traditional noise-control devices are often hampered by substantial size limitations,and their o...Acoustic wave isolation and noise reduction are significant challenges in the fields of physics and various applications.Traditional noise-control devices are often hampered by substantial size limitations,and their operational efficacy is generally restricted to planar waveforms.In this study,we demonstrate perfect confinement of acoustic vortex waves using an acoustic metacage consisting of phase-gradient metasurfaces.By leveraging the parity-reversed diffraction rule of phase-gradient metasurfaces,the designed metacage exhibited remarkable capabilities for the perfect confinement of acoustic vortex waves,showing robust performance even in the presence of source offsets.These findings present a promising strategy for developing precise and adaptable acoustic confinement technologies.展开更多
基金the Scientific Research Projects Unit of Erciyes University under contract no:FDS-2022-11532 and FOA-2025-14773.
文摘This paper examines a model that combines vortex generators and leading-edge tubercles for controlling the laminar separation bubble(LSB)over an airfoil at low Reynolds numbers(Re).This new concept of passive flow control technique utilizing a tubercle and vortex generator(VG)close to the leading edge was analyzed numerically for a NACA0015 airfoil.In this study,the Shear Stress Transport(SST)turbulence model was employed in the numerical modelling.Numerical modelling was completed using the ANSYS-Fluent 18.2 solver.Analyses were conducted to investigate the flow pattern and understand the underlying LSB control phenomena that enabled the new passive flow control method to provide this significant performance benefit.The findings indicated that the new concept of passive flow control technique suppressed the formation of an LSB at the suction surface of the NACA0015 airfoil,resulting in a higher lift coefficient and improved aerodynamic performance.Improvements in LSB dynamics and aerodynamic performance through the passive flow control method lead to increased energy output and enhanced stability.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDB0760300)the National Natural Science Foundation of China (Grant Nos.42175010 and 41875079)。
文摘Typhoon Bebinca in 2024 experienced a nearshore outbreak(a rapid intensification(RI)near the coast),making accurate forecasting of unpredictable tracks and intensities highly challenging.The AI model is superior to the numerical model for typhoon track prediction but performs worse for intensity forecasting.Vortex initialization is an effective approach to further improve numerical prediction via cycle assimilation,accounting for multiple relocating TC centers and adjusting the typhoon initial structure.In addition,by integrating numerical runs with an AI weather model through real-time dynamic weight correction of the forecast,the predictive skill is further improved.For example,it can reduce the deviation of 72-h track forecasting by 25%compared with the numerical model and decrease the intensity deviation by 2%and 56%relative to the numerical run and AI forecasts,respectively.On the basis of the best-performing forecasting,the inner-core convective burst(CB)characteristics are illuminated.The attributions of the nearshore outbreak and RI of Typhoon Bebinca are examined.From the viewpoint of bottom-up convection growth,the CB is associated with the energy supply from the high-boundarylayer CAPE,the following upward-developing secondary circulation,and accompanying latent heat release of hydrometeors.The contracted radius of maximum winds(RMW)and increased inertial stability within the inner core region effectively prevent the escape of the high-energy atmosphere and favor rapid intensification and maintenance of the offshore burst of a typhoon.The intensifying secondary circulation further promotes the primary circulation of the TC and RI processes through the gradient wind balance.
文摘This paper examines the connection between photonic band-gap formation in two types of two-dimensional photonic crystals and the emergence of reverse electromagnetic energy flows generated by linearly polarized plane waves incident on a photonic-crystal slab.We show that these reverse energy flows,observed in both transmitted and reflected fields,originate from vortex structures in the Poynting vector.The resulting energy-flow patterns exhibit striking analogies to vortex formation in fluid motion past obstacles.The geometry and dynamics of the Poynting-vector vortices determine whether the incident electromagnetic energy is impeded,leading to the formation of photonic band gaps,or instead guided through the structure,enabling transmission.
基金sponsored by the National Natural Science Foundation of China(Grant No.42275171)the Basic Research Operating Expenses of the Institute of Meteorological Sciences,CMA(Grant No.2023Z019)+3 种基金the National Key Research and Development Program of China(Grant No.2022YFF0801304)the China Meteorological Administration Youth Innovation Team Fund(Grant No.CMA2024QN05)a Liaoning Provincial Meteorological Bureau Project(Grant No.D202201)Shenyang Institute of Atmospheric Environment Projects(Grant Nos.2022SYIAEJY13 and 2018SYIAEZD5).
文摘The Northeast China Cold Vortex(NCCV)is a common cut-off low-pressure system in Northeast China,frequently causing localized heavy rainfall,strong winds,and thunderstorms during the early summer.In this study,the clear-sky radiance of 48 longwave channels from the FY-4B Geostationary Interferometric Infrared Sounder(GIIRS)is assimilated into the China Meteorological Administration mesoscale model(CMA-MESO)to evaluate its impact on NCCV development and its effects on rainfall forecasting.The results show that after assimilating the GIIRS radiance data,the warm center at 200 hPa and the cold center at 850 hPa of the NCCV are strengthened,and the dry intrusion at 850 hPa becomes more pronounced.This leads to a stronger NCCV intensity in the following 24 hours and brings the precipitation intensity and area closer to the observation,resulting in significant improvements compared to the experiments that do not assimilate GIIRS radiance data.Furthermore,it is found that the enhancement of the precipitation forecast is associated with the strengthening of cold air in the middle and lower troposphere,which intensifies the uplift of the warm,moist airflow.These results highlight the potential value of GIIRS data assimilation in enhancing early warnings and forecasts of extreme weather events influenced by the NCCV.
基金support from the National Natural Science Foundation of China(Grant No.12175215,Grant No.12475041)the National Key Research and Development Program of China(Grant No.2022YFA 1405300)NSAF(Grant No.U2330401)。
文摘We study Onsager vortex clustered states in a shell-shaped superfluid containing a large number of quantum vortices.In the incompressible limit and at low temperatures,the relevant problem can be boiled down to the statistical mechanics of neutral point vortices confined on a sphere.We analyze rotation-free vortex-clustered states within the mean-field theory in the microcanonical ensemble.We find that the sandwich state,which involves the separating of vortices with opposite circulation and the clustering of vortices with the same circulation around the poles and the equator,is the maximum entropy vortex distribution,subject to a zero angular momentum constraint.The dipole moment vanishes for the sandwich state and the quadrupole tensor serves as an order parameter to characterize the vortex cluster structure.For a given finite angular momentum,the equilibrium vortex distribution forms a dipole structure,i.e.,vortices with opposite sign are separated and accumulate around the south and north poles,respectively.The conditions for the onset of clustering and the exponents associated with the quadrupole moment and the dipole moment as functions of energy are obtained within the mean field theory.At large energies,we obtain asymptotically exact vortex density distributions using the stereographic projection method,yielding the parameter bounds for the vortex clustered states.The analytical predictions are in excellent agreement with microcanonical Monte Carlo simulations.
文摘By introducing noncanonical vortex pairs to partially coherent beams, spatial correlation singularity (SCS) and orbital angular momenta (OAM) of the resulting beams are studied using the Fraunhofer diffraction integral. The effect of noncanonical strength, off-axis distance and vortex sign on spatial correlation singularities in far field is stressed. Furthermore, far-field OAM spectra and densities are also investigated, and the OAM detection and crosstalk probabilities are discussed. The results show that the number of dislocations of SCS always equals the sum of absolute values of topological charges for canonical or noncanonical vortex pairs. Although the sum of the product of each OAM mode and its power weight equals the algebraic sum of topological charges for canonical vortex pairs, the relationship no longer holds in the noncanonical case except for opposite-charge vortex pairs. The changes of off-axis distance, noncanonical strength or coherence length can lead to a more dominant power in adjacent mode than that in center detection mode, which also indicates that crosstalk probabilities of adjacent modes exceed the center detection probability. This work may provide potential applications in OAM-based optical communication, imaging, sensing and computing.
基金supported by the National Key R&D Program of China(2022YFC3003903)Natural Science Foundation of Beijing(Grant No.8222079)and of China(Grant No.42475014,U2442204)the Basic Research Fund of CAMS(2023Z001).
文摘This study investigates extreme rainfall episodes along the eastern foothills of the Taihang Mountains in North China from 30 July to 1 August 2023.It focuses on two types of extreme hourly rainfall rates(HRRs),i.e.,the maximum regionalaverage HRR and site-observed HRR,which exhibited sequential development over southern,middle,and northern key regions.These rainfall extremes occurred in an environment where a high-pressure barrier over North China prevented the intrusion of cold air masses from the north while a northward-moving typhoon remnant vortex and its associated low-level jet(LLJ)transported warm and moist airflow from the south.Two distinct echo evolution modes and convection initiation mechanisms are identified for the two types of extreme HRRs.The maximum regional-average HRR occurred when the LLJ arrived to the east of the key regions,while the maximum site-observed HRR occurred when the warmer vortex center influenced the regions.Taking the northern key region as a representation,at the time of the maximum regional-average HRR,slantwise ascent of the airflow along a warm-frontal-like boundary released energy related to symmetrical instability,resulting in stratiform rainfall with weak convective cores.The transport of locally initiated convection over the eastern plain region,where the atmospheric stratification was more potentially unstable,also significantly contributed.When the maximum site-observed HRR occurred,the terrain lifting of warm and moist southeast airflow led to intense convection over the mountain foothills.Overall,the passage of the warm-core typhoon remnant vortex and interaction with Taihang Mountains determined the timing and location of extreme HRRs across the key regions.
基金supported by the National Natural Science Foundation of China(Grant No.52474339)Anhui Province Outstanding Research and Innovation Team in Higher Education Institutions(Grant No.2022AH010024).
文摘The free-surface vortex is a rotational flow phenomenon characterized by two-phase coupling,formed by the rupture of surface fluid in the final stage of discharge.It is a significant concept with broad applications in engineering fields like metallurgy and hydraulics.The basic concepts and characteristics of free-surface vortices were introduced,and their hazards in various fields were discussed.The development of theoretical and numerical models over recent decades was reviewed,and the factors affecting vortex formation and existing suppression methods were outlined.Finally,the key challenges and focus areas on the study of free-surface vortex were summarized.With the ongoing advancements in computational fluid dynamics and experimental technology,research on free-surface vortices will become more in depth and precise.Additionally,interdisciplinary cooperation and technological innovation are expected to achieve precise control and optimal design of free-surface vortices,offering more efficient and sustainable solutions for metallurgy and related engineering fields.
基金supported by the National Natural Science Foundation of China(Grant No.12105210)the Knowledge Innovation Program of Wuhan-Basi Research(Grant No.2023010201010149)。
文摘We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW structure interacts with a weak probe laser field,a spatially independent 2D standing-wave(SW)field,and a Laguerre–Gaussian(LG)vortex field,respectively.The results indicate that the diffraction patterns are highly sensitive to amplitude modulation and phase modulation.Because of the existence of vortex light,it is possible to realize asymmetric high-order diffraction in the SQW structure,and then a 2D asymmetric grating is established.By adjusting the detunings of the probe field,vortex field,and SW field,as well as the interaction length,diffraction intensity,and direction of the 2D asymmetric electromagnetically induced grating(EIG)can be controlled effectively.In addition,the number of orbital angular momenta(OAM)and beam waist parameter can be used to modulate the diffraction intensity and energy transfer of the probe light in different regions.High-order diffraction intensity is enhanced and high-efficiency 2D asymmetric diffraction grating with different diffraction patterns is obtained in the scheme.Such 2D asymmetric diffraction grating may be beneficial to the research of optical communication and innovative semiconductor quantum devices.
基金The derivation of the population coefficients in the emission induced by a plane wave are supported by the Foundation for the Advancement of Theoretical Physics and Mathematics“BASIS”The extension of these calculations to an incident vortex photon is supported by the Ministry of Science and Higher Education of the Russian Federation(Grant No.FSER-2025-0012)+2 种基金The studies of time dynamics of OAM of the entangled pair are supported by the Russian Science Foundation(Grant No.23-62-10026https://rscf.ru/en/project/23-6210026/)The studies of influence of the finite localization region of an atom on its interaction with an incident vortex photons are supported by the Russian Science Foundation(Grant No.25-71-00060)。
文摘Pairs of entangled vortex photons can promise new prospects of application in quantum computing and cryptography.We investigate the possibility of generating such states via two-level atom emission induced by a single photon wave packet with a definite total angular momentum(TAM).The entangled pair produced in this process possesses well-defined mean TAM with the TAM variation being much smaller than h.On top of that,the variation exponentially decreases with the increase in TAM of the incident photon.Our model allows one to track the time evolution of the state of the entangled pair.An experimentally feasible scenario is assumed,in which the incident photon interacts with a spatially confined atomic target.We conclude that induced emission can be used as a source of entangled vortex photons with applications in atomic physics experiments,quantum optics,and quantum information sciences.
基金supported by the National Natural Science Foundation of China(Nos.92271110,12072352)the Major National Science and Technology Project,China(No.J2019-Ⅲ-0010-0054)。
文摘To delay the vortex breakdown position of the slender delta wing,this study innovativelyproposes the application of control near the Leading-Edge Vortex(LEV)core sweeping path,whichis called Coupled Core Rotation Dual Synthetic Jets(CCR-DSJ)control.The results show that thevortex breakdown points at each angle of attack are moved backward after control,and the max-imum delayed displacement is 32.4%of the root chord at 30°.Besides,there is a linear relationshipbetween the breakdown position and the angle of attack after control,indicating that CCR-DSJcontrol has a significant effect on the pressure gradient of the vortex axis.Furthermore,the lift coef-ficient C_(L)is enhanced after control,with a maximum CLincrement of 0.078 at 27°,and an effectiveincrement interval of[25°,32°].This interval is different from most previous studies,which isdirectly related to the position of the actuators.According to the lift change mechanism,the anglesof attack are divided into three stages:Stage 1(a=15°–25°),Stage 2(a=25°–32°),and Stage 3(a=32°–40°).In conclusion,CCR-DSJ control can significantly change the pressure distribution,thereby offering promising prospects for the flight stage of the slender delta wing.
基金supported by the Natural Science Foundation of Hubei Province of China(Grant No.2025AFB370)。
文摘The vortex dynamics after the initial ring dark solitons in two-component ultracold Rydberg atomic systems have been investigated.The two parameters characterizing the Rydberg long-range interaction—namely,the Rydberg strength and the blockade radius—along with the initial depth,are identified as the main factors that affect the vortex dynamics.In the absence of Rydberg soft-core potential and spin-orbit coupling,the late vortex dipoles move along x-or y-axis first.However,this work demonstrates that,with certain Rydberg strength and blockade radius,the late vortex dipoles move towards the edge at an oblique angle to the coordinate axes,and it reveals that the Rydberg nonlocal nonlinear interaction shortens the lifetime of late vortices.When the intra-component and inter-component Rydberg strengths are different,the backgrounds of the two components gradually complement each other,and the lifetime of late vortices is significantly shortened.The presented results show that the Rydberg dressing breaks the rule that the initial average depth determines the number and paths of vortices.The motion features of vortex dipoles in the ultracold Rydberg atomic system have been ascertained,and their directions of movement can be predicted to some degree based on the rotation directions and initial positions of the vortices.
基金supported in part by the National Key R&D Program(Grant No.2023YFA1606900)the National Natural Science Foundation of China(Grant No.12235003)。
文摘Chirality,a common phenomenon in nature,appears in structures ranging from galaxies and condensed matter to atomic nuclei.There is a persistent demand for new,high-precision methods to detect chiral structures,particularly at the microscale.Here,we propose a novel method,vortex Mössbauer spectroscopy,for probing chiral structures.By leveraging the orbital angular momentum carried by vortex beams,this approach achieves high precision in detecting chiral structures at scales ranging from nanometers to hundreds of nanometers.Our simulation shows the ratio of characteristic lines in the Mössbauer spectra of ^(57)Fe under vortex beams exhibits differences of up to four orders of magnitude for atomic structures with different arrangements.Additionally,simulations reveal the response of ^(229m)Th chiral structures to vortex beams with opposite angular momenta differs by approximately 49-fold.These significant spectral variations indicate that this new vortex Mössbauer probe holds great potential for investigating the microscopic chiral structures and interactions of matter.
基金supported by the National Natural Science Foundation of China(Nos.U2333209,U1733203)the National Key R&D Program of China(No.2021YFF0603904)the Civil Aviation Administration of China(No.AQ20200019)。
文摘Regional turbofan aircraft,which are used for medium-short distances,have a heightened risk of high-altitude Wake Vortices(VV)because of their tail-mounted engines and high horizontal tail configurations.For some regional medium-short-range turbofan aircraft,this threat is higher than that for conventionally designed aircraft.To analyze the flight safety of turbofan aircraft during cruise,this study developed a model to assess wake vortex encounters based on evolutionary high-altitude wake flow patterns.First,the high-altitude wake vortex aircraft dissipation patterns were analyzed by combining Quick Access Recorder(QAR)flight data with the wake vortex evolution model.Then,to consider the uniqueness of the medium-short-range turbofan aircraft,the severity of the wake vortex encounters was simulated using an induced roll moment coefficient.The proposed high-altitude wake vortex encounter model was able to identify and assess the highaltitude wake vortex changes,the bearing moments at different altitudes,and the atmospheric pressure conditions.Using the latest wake separation standards from the International Civil Aviation Organization(ICAO),acceptable safety wake intervals for follower aircraft in different scenarios were determined for the safety assessment.The results indicate that compared to mid and low altitudes,the high-altitude aircraft wake vortex dissipation rate is faster,the ultimate bearing moment is weaker,and the roll moment coefficient is higher,which confirm that there is elevated wake vortex encounter severity for regional turbofan aircraft.As safety is found to deteriorate when encountering wake vortices at altitudes higher than 8 km,new medium-short-range turbofan regional aircraft require higher safety margins than the latest wake separation standards.
基金supported by the National Key Research Program of China(Grant Nos.2021YFA1401900,2022YFA1403300,and 2020YFA0309100)the Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0302602 and 2024ZD0300103)+1 种基金the National Natural Science Foundation of China(Grant No.12074073)for samplefabrication and measurementthe support by the The Basic Research Program of the Chinese Academy of Sciences Based on Major Scientific Infrastructures(Grant No.JZHKYPT-2021-08).
文摘When a perpendicular magnetic field penetrates a thin slab of a type-Ⅱ superconductor it produces vortices,with one vortex per flux quantum,h/2e.The vortices interact repulsively and form an ordered array(Abrikosov lattice)in clean systems,while strong disorder changes the lattice into a vortex glass.The collective vortex dynamics is extremely vulnerable to external perturbations.Consequently,although of great importance,experimental observation is limited.Here we investigate type-Ⅱ superconducting films(PdBi_(2)and NbSe_(2))with surface acoustic waves(SAWs)at mK temperature.When sweeping the magnetic field at an extremely slow rate,we observe a series of spikes in the attenuation and velocity of the SAW,on average separated in field by approximately Hc1.We propose the following scenario:The vortex-free region at the edges of the film produces an edge barrier across which the vortices can enter or leave.When the applied field changes,the induced supercurrents flowing along this edge region lowers this barrier until there is an instability.At that point,vortices avalanche into(or out of)the bulk and change the vortex crystal,suggested by the sharp jump in each such spike.The vortices then gradually relax to a new stable pinned configuration,leading to a~30 s relaxation after the jump.Our observation enriches the limited experimental evidence on the important topic of real-time vortex dynamics in superconductors.
文摘The present study investigates the non-isothermal flow and energy distribution through a loosely bent rectangular duct using a spectral-based numerical approach over a wide range of the Dean number 0<Dn≤3000.Unlike previous research,this work offers novel insights by conducting a grid-point-specific velocity analysis and identifying new bifurcation structures.The study reveals how centrifugal and buoyancy forces interact to produce steady,periodic,and chaotic flow regimes significantly influencing heat transfer performance.The Newton-Raphson method is employed to explore four asymmetric steady branches,with vortex solutions ranging from 2-to 12 vortices.Unsteady flow characteristics are analyzed exquisitely by performing time-advancement of the solutions and the flow regimes are shown as a percentage of total flow with longitudinal vortex generation.Axial flow,secondary flow,and temperature profiles have been depicted in accordance with Dn to wander the flow pattern,and it is predicted that the time-dependent flow(TDF)consists of asymmetric 2-to 10-vortex solutions.The significant findings of this study include the axial displacement of the circulations due to the influence of the time-varying temperature dispersal applied along the wall.Chaotic flows,which dominate the higher Dean number range,are shown to enhance heat convection due to increased fluid mixing.A detailed comparison with prior research demonstrates the advantages of this approach,particularly in capturing complex non-linear behaviors.The findings of this study provide practical guidelines for optimizing duct designs to maximize heat transfer and suggest future research directions,such as using nanofluids or studying Magneto-hydrodynamics in the same configuration.
基金supported in part by National Natural Science Foundation of China under Grant 62441115 and 62201427in part by the Ministry of Industry and Information Technology of the People’s Republic of China under Grant CBG01N23-01-04.
文摘Orbital angular momentum(OAM)can achieve multifold increase of spectrum efficiency,but the hollow divergence characteristic and Line-of-Sight(LoS)path requirement impose the crucial challenges for vortex wave communications.For air-to-ground vortex wave communications,where there exists the LoS path,this paper proposes a multi-user cooperative receive(MUCR)scheme to break through the communication distance limitation caused by the characteristic of vortex wave hollow divergence.In particular,we derive the optimal radial position corresponding to the maximum intensity,which is used to adjust the waist radius.Based on the waist radius and energy ring,the cooperative ground users having the minimum angular square difference are selected.Also,the signal compensation scheme is proposed to decompose OAM signals in air-to-ground vortex wave communications.Simulation results are presented to verify the superiority of our proposed MUCR scheme.
基金supported by the National Natural Science Foundation of China(Grant No.62275075)the Natural Science Foundation of Hubei Soliton Research Association(Grant No.2025HBSRA09)+1 种基金joint supported by Hubei Provincial Natural Science Foundation and Xianning of China(Grant Nos.2025AFD401 and 2025AFD405)Israel Science Foundation(Grant No.1695/22).
文摘We propose a theoretical framework,based on the two-component Gross-Pitaevskii equation(GPE),for the investigation of vortex solitons(VSs)in hybrid atomic-molecular Bose-Einstein condensates under the action of the stimulated Raman-induced photoassociation and square-optical-lattice potential.Stationary solutions of the coupled GPE system are obtained by means of the imaginary-time integration,while the temporal dynamics are simulated using the fourth-order Runge-Kutta algorithm.The analysis reveals stable rhombus-shaped VS shapes with topological charges m=1 and 2 of the atomic component.The stability domains and spatial structure of these VSs are governed by three key parameters:the parametric-coupling strength(χ),atomicmolecular interaction strength(g_(12)),and the optical-lattice potential depth(V_(0)).By varyingχand g_(12),we demonstrate a structural transition where four-core rhombus-shaped VSs evolve into eight-core square-shaped modes,highlighting the nontrivial nonlinear dynamics of the system.This work establishes a connection between interactions of cold atoms and topologically structured matter waves in hybrid quantum systems.
基金National Natural Science Foundation of China(22178228,22178326)
文摘A cylindrical chamber with a rotating bottom holds significant potential for application in cell culture bioreactors due to its ability to generate more stable swirling flows.In order to control vortex breakdown within the chamber,this study first establishes a computational fluid dynamics simulation coupled with the level set method.Verified by experimental results in literature,this method accurately simulates the position and shape of vortex breakdown,and also predicts the critical Reynolds numbers for the appearance and detachment of vortex breakdown bubbles from the center.Additionally,it precisely captures the gas-liquid interface and depicts the vortex breakdown phenomenon in the air above the liquid for the first time.Finally,it predicts the impact of physical property of gas-liquid systems on vortex breakdown in response to significant changes in viscosity of microbial process systems.
基金supported by the Undergraduate Training Program for Innovation and Entrepreneurship,Soochow University(Grant No.202410285001Z)the National Natural Science Foundation of China(Grant Nos.12274313 and 12374293)。
文摘Acoustic wave isolation and noise reduction are significant challenges in the fields of physics and various applications.Traditional noise-control devices are often hampered by substantial size limitations,and their operational efficacy is generally restricted to planar waveforms.In this study,we demonstrate perfect confinement of acoustic vortex waves using an acoustic metacage consisting of phase-gradient metasurfaces.By leveraging the parity-reversed diffraction rule of phase-gradient metasurfaces,the designed metacage exhibited remarkable capabilities for the perfect confinement of acoustic vortex waves,showing robust performance even in the presence of source offsets.These findings present a promising strategy for developing precise and adaptable acoustic confinement technologies.
