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
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
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
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
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 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
Using long-term Whole Atmosphere Community Climate Model version 5(WACCM5)simulations initialized with the climatology around the year 2000,we studied the anomalous distribution of planetary wave and gravity wave flux...Using long-term Whole Atmosphere Community Climate Model version 5(WACCM5)simulations initialized with the climatology around the year 2000,we studied the anomalous distribution of planetary wave and gravity wave fluxes during distinct phases of the boreal stratospheric polar vortex(BSPV)and Quasi-Biennial Oscillation(QBO).The contributions of these two types of waves to Brewer-Dobson circulation(BDC)anomalies were further analyzed.The results revealed that under four distinct phases,the northern hemisphere BDC is primarily governed by planetary waves,whereas gravity waves counteract approximately half of the planetary wave influence on the BDC in the upper stratosphere.The QBO regulates the position of the anomaly center within the BDC’s descending branch in the northern hemisphere.In particular,during the westerly phase of the QBO(WQBO),the center of this anomalous descending branch is located in the upper stratosphere,whereas during the easterly phase of the QBO(EQBO),it is located in the lower stratosphere.Southern hemisphere BDC anomalies are regulated more by QBO activity:during the WQBO,it shows synchronous changes with the BDC anomaly in the northern hemisphere,whereas during the EQBO,it exhibits an antiphase relationship with the BDC anomaly in the northern hemisphere.Mesospheric circulation anomalies are predominantly driven by gravity wave activity.The circulation weakens during a weak BSPV and strengthens during a strong BSPV.Additionally,the descending branch anomaly of the northern hemisphere circulation is more pronounced during the WQBO,whereas the ascending branch anomaly of the southern hemisphere circulation is more significant during the EQBO.展开更多
We aim to find one highly nontrivial example of the solutions to the vortex fluid dynamical equation on the unit sphere(S^(2))and compare it with the numerical simulation.Since the rigid rotating steady solution for v...We aim to find one highly nontrivial example of the solutions to the vortex fluid dynamical equation on the unit sphere(S^(2))and compare it with the numerical simulation.Since the rigid rotating steady solution for vortex fluids on S^(2)is already known to us,we consider the perturbations above it.After decomposing the perturbation of the vortex number density and vortex charge density into spherical harmonics,we find that the perturbations are propagating waves.To be precise,the velocities for different single-mode vortex number density waves are all the same,while the velocities for single-mode vortex charge density waves depend on the degree of the spherical harmonics l,which is a signal of the existence of dispersion.Meanwhile,we find that there is a beat phenomenon for the positive(or negative)vortex density wave.Numerical simulation based on the canonical equations for the point vortex model agrees perfectly with our theoretical calculations.展开更多
Techniques for manipulating nanodroplets lie at the core of numerous miniaturized systems in chemical and biological research endeavors.In this study,we introduce a versatile methodology for calculating the acoustic v...Techniques for manipulating nanodroplets lie at the core of numerous miniaturized systems in chemical and biological research endeavors.In this study,we introduce a versatile methodology for calculating the acoustic vortex field,integrating hybrid wave equation principles with ray acoustics.This approach demonstrates remarkable consistency between simulated results and experimental observations.Importantly,both theoretical analysis and experimental validation confirm that particles whose diameters match the wavelength(Mie particles)can be effectively trapped within a focused acoustic vortex field,rotating in circular trajectories centered at the vortex center.This research significantly expands the scope of acoustic vortex manipulation for larger particles and introduces a novel implementation strategy with potential applications in targeted drug delivery for clinical adjuvant therapy.展开更多
Manipulating and braiding Majorana zero modes(MZM)are a critical step toward realizing topological quantum computing.The primary challenge is controlling the vortex,which hosts the MZM,within a superconducting film in...Manipulating and braiding Majorana zero modes(MZM)are a critical step toward realizing topological quantum computing.The primary challenge is controlling the vortex,which hosts the MZM,within a superconducting film in a spatially precise manner.To address this,we developed a magnetic force-based vortex control technology using the STM system with a self-designed four-electrode piezo-scanner tube and investigated vortex manipulation on the NbSe_(2) superconducting film.We employed ferromagnetic tips to control the movement of vortex array induced by the tip's remanent magnetism.A magnetic core solenoid device was integrated into the STM system and a strong magnetic tip demagnetization technique was developed,providing a viable technical solution for further enabling single vortex manipulation.展开更多
The stratospheric Arctic vortex(SAV)plays a critical role in forecasting cold winters in the northern midlatitudes.In this study,we systematically examined the responses of SAV intensity to regional sea surface temper...The stratospheric Arctic vortex(SAV)plays a critical role in forecasting cold winters in the northern midlatitudes.In this study,we systematically examined the responses of SAV intensity to regional sea surface temperature(SST)changes using idealized SST patch experiments with a climate model.Our findings reveal that the SAV intensity is most sensitive to SST variations in the tropics and northern midlatitudes during boreal winter(December-January-February).Specifically,warming in the tropical Pacific and Atlantic leads to a weakening of the SAV,while warming in the tropical Indian Ocean,northern midlatitude Atlantic,and northwestern Pacific strengthens the SAV.Notably,the most substantial SAV weakening(strengthening)is triggered by warming in the tropical western Pacific(tropical central Indian Ocean),with a maximum magnitude of approximately 2.23 K K^(-1)(-1.77 K K^(-1)).The SST warming in the tropics influences the tropical convections,which excite Rossby wave trains.These wave trains can interfere with the climatological waves in the mid-high latitudes,while the SST warming in the northern midlatitudes can influence tropospheric planetary wavenumber-1 and wavenumber-2 directly.The changes in tropospheric planetary waves modulate the upward propagation of wave activities and impact the SAV intensity.Additionally,the response of the SAV to tropical SST changes,especially over the Indian Ocean and subtropics,exhibits significant nonlinearity.展开更多
The Vortex Particle Method(VPM)is a meshless Lagrangian vortex method.Its low numerical dissipation is exceptionally suitable for wake simulation.Nevertheless,the inadequate numerical stability of VPM prevents its wid...The Vortex Particle Method(VPM)is a meshless Lagrangian vortex method.Its low numerical dissipation is exceptionally suitable for wake simulation.Nevertheless,the inadequate numerical stability of VPM prevents its widespread application in high Reynolds number flow and shear turbulence.To better simulate these flows,this paper proposes the stability-enhanced VPM based on a Reformulated VPM(RVPM)constrained by conservation of angular momentum,integrating a relaxation scheme to suppress the divergence of the vorticity field,and further coupling the Sub-Grid Scale(SGS)model to account for the turbulence dissipation caused by vortex advection and vortex stretching.The validity of the RVPM is confirmed by simulating an isolated vortex ring's evolution.The results also demonstrate that the relaxation scheme of vorticity enhances the numerical stability of the VPM by mitigating the divergence of the vorticity field.The leapfrogging vortex rings simulation demonstrates that the RVPM with the present SGS model can more precisely feature the leapfrog and fusion of vortex rings and has improved numerical stability in high Reynolds number flows.The round turbulent jet simulation confirms that the stability-enhanced VPM can stably simulate shear turbulence and accurately resolve fluctuating components and Reynolds stresses in the turbulence.展开更多
Deepwater drilling riser is the key equipment connecting the subsea wellhead and floating drilling platform.Due to complex marine environment,vortex-induced vibration(ViV)will be generated on riser,which will induce f...Deepwater drilling riser is the key equipment connecting the subsea wellhead and floating drilling platform.Due to complex marine environment,vortex-induced vibration(ViV)will be generated on riser,which will induce fatigue failure and even cause unpredictable drilling accidents.Therefore,it is important to study the ViV characteristics of deepwater drilling riser and reveal the main controlling factors for ensuring the safe and efficient operation of deepwater drilling engineering.In this paper,the ViV of deepwater drilling riser is numerically simulated in time domain based on the discrete vortex method(DvM).A hydrodynamic analysis model and governing equation of VIV is proposed with considering the effect of riser motion using DVM and slice method,where the governing equation is solved by Runge-Kutta method.Model validation is performed,which verified the correctness and accuracy of the mechanical model and the solution method.On this basis,the influence of the number of control points,current velocity,riser outer diameter,shear flow and top tension on the ViV characteristics of deepwater drilling risers are discussed in detail.The results show that with the increase of current velocity,the vibration amplitude of deepwater drilling riser decreases obviously,while the vibration frequency increases gradually.However,if the outer diameter of riser increases,the vibration amplitude increases,while the vibration frequency decreases gradually.The top tension also has great influence on the VIV of riser.When the top tension is 1.25 G,the VIV is suppressed to a certain extent.This study has guiding significance for optimal design and engineering control of deepwater drilling riser.展开更多
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 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 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 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 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.
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.
基金supported by the National Natural Science Foundation of China(Grant Nos.U244221042475072 and 42361144843).
文摘Using long-term Whole Atmosphere Community Climate Model version 5(WACCM5)simulations initialized with the climatology around the year 2000,we studied the anomalous distribution of planetary wave and gravity wave fluxes during distinct phases of the boreal stratospheric polar vortex(BSPV)and Quasi-Biennial Oscillation(QBO).The contributions of these two types of waves to Brewer-Dobson circulation(BDC)anomalies were further analyzed.The results revealed that under four distinct phases,the northern hemisphere BDC is primarily governed by planetary waves,whereas gravity waves counteract approximately half of the planetary wave influence on the BDC in the upper stratosphere.The QBO regulates the position of the anomaly center within the BDC’s descending branch in the northern hemisphere.In particular,during the westerly phase of the QBO(WQBO),the center of this anomalous descending branch is located in the upper stratosphere,whereas during the easterly phase of the QBO(EQBO),it is located in the lower stratosphere.Southern hemisphere BDC anomalies are regulated more by QBO activity:during the WQBO,it shows synchronous changes with the BDC anomaly in the northern hemisphere,whereas during the EQBO,it exhibits an antiphase relationship with the BDC anomaly in the northern hemisphere.Mesospheric circulation anomalies are predominantly driven by gravity wave activity.The circulation weakens during a weak BSPV and strengthens during a strong BSPV.Additionally,the descending branch anomaly of the northern hemisphere circulation is more pronounced during the WQBO,whereas the ascending branch anomaly of the southern hemisphere circulation is more significant during the EQBO.
基金supported by the Scientific research projects of Hunan Provincial Department of Education(Grant Nos.22A0477 and 20B273)。
文摘We aim to find one highly nontrivial example of the solutions to the vortex fluid dynamical equation on the unit sphere(S^(2))and compare it with the numerical simulation.Since the rigid rotating steady solution for vortex fluids on S^(2)is already known to us,we consider the perturbations above it.After decomposing the perturbation of the vortex number density and vortex charge density into spherical harmonics,we find that the perturbations are propagating waves.To be precise,the velocities for different single-mode vortex number density waves are all the same,while the velocities for single-mode vortex charge density waves depend on the degree of the spherical harmonics l,which is a signal of the existence of dispersion.Meanwhile,we find that there is a beat phenomenon for the positive(or negative)vortex density wave.Numerical simulation based on the canonical equations for the point vortex model agrees perfectly with our theoretical calculations.
基金Project supported by the National Key R&D Program of China(Grant No.2023YFE0201900)。
文摘Techniques for manipulating nanodroplets lie at the core of numerous miniaturized systems in chemical and biological research endeavors.In this study,we introduce a versatile methodology for calculating the acoustic vortex field,integrating hybrid wave equation principles with ray acoustics.This approach demonstrates remarkable consistency between simulated results and experimental observations.Importantly,both theoretical analysis and experimental validation confirm that particles whose diameters match the wavelength(Mie particles)can be effectively trapped within a focused acoustic vortex field,rotating in circular trajectories centered at the vortex center.This research significantly expands the scope of acoustic vortex manipulation for larger particles and introduces a novel implementation strategy with potential applications in targeted drug delivery for clinical adjuvant therapy.
基金Project supported by the National Key Research&Development Program of China(Grant Nos.2019YFA0308600 and 2020YFA0309000)the National Natural Science Foundation of China(Grant Nos.92365302,92065201,22325203,92265105,12074247,12174252,52102336)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB28000000)the Science and Technology Commission of Shanghai Municipality(Grant Nos.2019SHZDZX01,19JC1412701,20QA1405100,24LZ1401000,LZPY2024-04)financial support from the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302500)。
文摘Manipulating and braiding Majorana zero modes(MZM)are a critical step toward realizing topological quantum computing.The primary challenge is controlling the vortex,which hosts the MZM,within a superconducting film in a spatially precise manner.To address this,we developed a magnetic force-based vortex control technology using the STM system with a self-designed four-electrode piezo-scanner tube and investigated vortex manipulation on the NbSe_(2) superconducting film.We employed ferromagnetic tips to control the movement of vortex array induced by the tip's remanent magnetism.A magnetic core solenoid device was integrated into the STM system and a strong magnetic tip demagnetization technique was developed,providing a viable technical solution for further enabling single vortex manipulation.
基金the financial support of National Key Research and Development Program of China(No.2022YFF0801701)National Natural Science Foundation of China(Grants 42375070)。
文摘The stratospheric Arctic vortex(SAV)plays a critical role in forecasting cold winters in the northern midlatitudes.In this study,we systematically examined the responses of SAV intensity to regional sea surface temperature(SST)changes using idealized SST patch experiments with a climate model.Our findings reveal that the SAV intensity is most sensitive to SST variations in the tropics and northern midlatitudes during boreal winter(December-January-February).Specifically,warming in the tropical Pacific and Atlantic leads to a weakening of the SAV,while warming in the tropical Indian Ocean,northern midlatitude Atlantic,and northwestern Pacific strengthens the SAV.Notably,the most substantial SAV weakening(strengthening)is triggered by warming in the tropical western Pacific(tropical central Indian Ocean),with a maximum magnitude of approximately 2.23 K K^(-1)(-1.77 K K^(-1)).The SST warming in the tropics influences the tropical convections,which excite Rossby wave trains.These wave trains can interfere with the climatological waves in the mid-high latitudes,while the SST warming in the northern midlatitudes can influence tropospheric planetary wavenumber-1 and wavenumber-2 directly.The changes in tropospheric planetary waves modulate the upward propagation of wave activities and impact the SAV intensity.Additionally,the response of the SAV to tropical SST changes,especially over the Indian Ocean and subtropics,exhibits significant nonlinearity.
基金co-supported by the National Natural Science Foundation of China(No.12402272)the Natural Science Basic Research Program of Shaanxi Province,China(No.2024JC-YBQN-0024)the Fundamental Research Funds for the Central Universities,China(No.D5000240030)。
文摘The Vortex Particle Method(VPM)is a meshless Lagrangian vortex method.Its low numerical dissipation is exceptionally suitable for wake simulation.Nevertheless,the inadequate numerical stability of VPM prevents its widespread application in high Reynolds number flow and shear turbulence.To better simulate these flows,this paper proposes the stability-enhanced VPM based on a Reformulated VPM(RVPM)constrained by conservation of angular momentum,integrating a relaxation scheme to suppress the divergence of the vorticity field,and further coupling the Sub-Grid Scale(SGS)model to account for the turbulence dissipation caused by vortex advection and vortex stretching.The validity of the RVPM is confirmed by simulating an isolated vortex ring's evolution.The results also demonstrate that the relaxation scheme of vorticity enhances the numerical stability of the VPM by mitigating the divergence of the vorticity field.The leapfrogging vortex rings simulation demonstrates that the RVPM with the present SGS model can more precisely feature the leapfrog and fusion of vortex rings and has improved numerical stability in high Reynolds number flows.The round turbulent jet simulation confirms that the stability-enhanced VPM can stably simulate shear turbulence and accurately resolve fluctuating components and Reynolds stresses in the turbulence.
基金the financial support from National Key R&D Program of China(Grant number:2024YFC2815100)Natural Science Foundation of China(Grant number:52322110)Beijing Nova Program(Grant number:20230484341).
文摘Deepwater drilling riser is the key equipment connecting the subsea wellhead and floating drilling platform.Due to complex marine environment,vortex-induced vibration(ViV)will be generated on riser,which will induce fatigue failure and even cause unpredictable drilling accidents.Therefore,it is important to study the ViV characteristics of deepwater drilling riser and reveal the main controlling factors for ensuring the safe and efficient operation of deepwater drilling engineering.In this paper,the ViV of deepwater drilling riser is numerically simulated in time domain based on the discrete vortex method(DvM).A hydrodynamic analysis model and governing equation of VIV is proposed with considering the effect of riser motion using DVM and slice method,where the governing equation is solved by Runge-Kutta method.Model validation is performed,which verified the correctness and accuracy of the mechanical model and the solution method.On this basis,the influence of the number of control points,current velocity,riser outer diameter,shear flow and top tension on the ViV characteristics of deepwater drilling risers are discussed in detail.The results show that with the increase of current velocity,the vibration amplitude of deepwater drilling riser decreases obviously,while the vibration frequency increases gradually.However,if the outer diameter of riser increases,the vibration amplitude increases,while the vibration frequency decreases gradually.The top tension also has great influence on the VIV of riser.When the top tension is 1.25 G,the VIV is suppressed to a certain extent.This study has guiding significance for optimal design and engineering control of deepwater drilling riser.
