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vortex Evolution Behavior in Self-Assembly of Flow Units in Metallic Glasses

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Acta Mechanica Solida Sinica 2023年第5期36卷 603-611页

作者： Jie Lian Ruyue Song Yan Chen Lanhong Dai State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

Shear banding in amorphous metals originates from the activation and percolation of flow *** uncover the self-assembly dynamics of flow units in metallic glasses,a rectangular sample with two flow units embedded in the matrix undergoing simple shearing was analyzed using finite element *** vortex evolution behavior,including activation,growth,and collapse during the self-assembly of flow units,was *** was found that the formation of a mature vortex indicates the onset of yielding,and the collapse of the vortex represents the percolation of flow units or shear *** effects of initial free volume distribution and the distance between flow units on vortex behavior were also *** the initial free volume concentration within flow units or the matrix leads to a gentler vortex evolution process and better homogeneous *** shape of vortex tends to be"flatter"with the increase in flow units'spacing,and the optimal spacing was found to maximize the strength of the material.

关键词： vortex Free volume Self-assembly Flow units Metallic glasses

vortex bound states influenced by the Fermi surface anisotropy

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Chinese Physics B 2023年第3期32卷 497-501页

作者：方德龙 Department of Mathematics and Physics Nanjing Institute of TechnologyNanjing 211167China

The spatial distribution of vortex bound states is often anisotropic,which is correlated with the underlying property of *** this work,we examine the effects of Fermi surface anisotropy on vortex bound *** large-scale calculation of vortex bound states is introduced in the presence of fourfold or twofold Fermi surface by solving the Bogoliubov–de Gennes(BdG)*** kinds of quasiparticles’behaviors can be extracted from the local density of states(LDOS)around a *** angle-dependent quasiparticles will move from high energy to low energy when the angle varies from curvature maxima to minima of the Fermi surface,while the angle-independent quasiparticles tend to stay at a relatively higher *** addition,the weight of angle-dependent quasiparticles can be enhanced by the increasing anisotropy degree of Fermi surface.

关键词： vortex anisotropy Fermi surface local density of states

Sediment bed destabilization by an isolated vortex:an experimental approach

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Journal of Hydrodynamics 2021年第2期33卷 370-385页

作者： Yann Devaux Lionel Thomas Damien Calluaud Gérard Pineau Institut Pprime CNRS-Universitéde Poitiers-ISAE-ENSMA-UPR 3346PoitiersFrance

The destabilization of an erodible sediment bed by a reproducible impulsive phenomenon is studied *** this,a specific setup is designed to produce a well-controlled isolated vortex,advected over a uniform sand *** image velocimetry(PIV)measurements are performed to get fluid flow information;suspended particles images are also recorded.A new measurement technique,based on a stereo-correlation method,provides a precise reconstruction of the bedform morphology over *** turbulent structures(namely sweep events)are evidenced in a near-wall region,where particles are mainly *** sediment plume follows the vortex:in particular,the upward velocity inside maintains the suspension ***,the dispersion process seems to be not dependent on the vortex ***,the bed morphology is investigated:a scour hole is dug as the vortex hits the granular *** dynamics is described by a typical scour law,even if the initial perturbation is *** area,where the particles settled,can be observed:it behaves like a ripple,with a logarithmic growth of its *** deposition region has a specific geometry,studied here by a Fourier contour ***,a pickup rate is also derived from the morphological data:it appears independent of the vortex and bedform features.

关键词： Sediment plume isolated vortex stereo-correlation particle image velocimetry(PIV) bedform dynamics

vortex Street in Homogeneous Dense Dusty Magnetoplasma

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Communications in Theoretical Physics 2014年第12期61卷 871-874页

作者：杨建荣吴波毛杰键刘萍王建勇 School of Physics and Electronic Information Shangrao Normal University Department of Physics and Astronomy Shanghai Jiao Tong University College of Electron and Information Engineering University of Electronic Science and Technology of China Zhongshan Institute

For studying the vortex structure in uniform dense dusty astrophysical conditions, a two-dimensional nonlinear equation is derived employing the quantum magnetoplasma hydrodynamic model and considering the strong collisional effect. The coherent vortex solution is obtained by perturbation analysis method. It is shown that the distribution of the electrostatic potential forms spatially a periodic vortex street, and is controlled temporally by the arbitrary function of time that may lead to abundant spacial distributions. It is found that the dust charge number,collision frequency, electron Fermi wavelength and quantum correction all play significant roles to the spatial distribution of vortex street.

关键词： dusty magnetoplasma quantum hydrodynamic model vortex street

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Journal of Hydrodynamics 2008年第6期20卷 679-688页

作者： BOSSCHERS J JANSSEN A. A. HOEIJMAKERS H. W. M. Maritime Research Institute Netherlands (MARIN) P.O. Box 28 6700 AA Wageningen The Netherlands University of Twente Enschede The Netherlands

Theoretical analysis of the dynamic behavior of cavitating vortices requires knowledge of the velocity distribution in the vortex core. For that reason an existing similarity model for slender axisymmetric non-cavitating vortex cores has been extended with the viscous boundary conditions for a cavitating vortex. Cavitating similarity solutions exist for a vortex of which both core diameter and circulation grow with the square root of the axial coordinate. Results for this model are presented for varying cavitation numbers and Reynolds numbers. It is shown that viscosity may have a significant influence on the velocity distribution around a cavitating vortex.

关键词： cavitation vortex viscous flow

The applicability of vortex identification methods for complex vortex structures in axial turbine rotor passages

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Journal of Hydrodynamics 2019年第4期31卷 700-707页

作者： Yu-fan Wang Wei-hao Zhang Xia Cao Hong-kai Yang National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics School of Energy and Power Engineering Beihang University Beijing 100191 China Collaborative Innovation Center of Advanced Aero-Engine Beijing 100191 China

The complex vortex structures in the flow around turbine rotor passages, with weak or strong, large or small vortices, interacting with each other, often generate most of aerodynamic loss in turbomachines. Therefore, it is important to identify the vortex structures accurately for the flow field analysis and the aerodynamic performance optimization for turbomachines. In this paper, by using 4 vortex identification methods (the Q criterion, the Q method, the Liutex method and the Q -Liutex method), the vortices are identified in turbine rotor passages. In terms of the threshold selection, the results show that the D method and the Q -Liutex method are more robust, by which strong and weak vortices can be visualized simultaneously over a wide range of thresholds. As for the display consistency of the vortex identification methods and the streamlines, it is shown that the Liutex method gives results coinciding best with the streamlines in identifying strong vortices, while the Q -Liutex method gives results the most consistent with the streamlines in identifying weak vortices. As to the relationship among the loss, the vortices and the shear, except for the Q criterion, the other three methods can distinguish the vortical regions from the high shear regions. And the flow losses in turbine rotor passages are often related to high shear zones, while there is a small loss within the core of the vortex. In order to obtain the variation of vortices in the turbine rotor passages at different working points, the Liutex method is applied in 2 cases of a turbine with different angles of attack. The identification results show that the strengths of the tip leakage vortex and the upper passage vortex are weaker and the distance between them is closer at a negative angle of attack. This indicates that the Liutex method is an effective method, and can be used to analyze the vortex structures and their evolution in turbine rotor passages.

关键词： vortex identification tip leakage vortex turbine rotor passage Liutex method Q -Liutex method

Streamwise vortex generation by the rod

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Chinese Journal of Aeronautics 2019年第8期32卷 1903-1911页

作者： Ryszard SZWABA Pawel FLASZYNSKI Piotr DOERFFER Department of Experimental Aerodynamics Institute of Fluid Flow Machinery Polish Academy of Sciences

The technology development related to aerodynamics is leading to ever increasing loads of wings, airfoils and turbine and compressor blades. The increase in aerodynamic forces is often leading to flow separation and depreciation of the aerodynamic performance of flying objects or propulsion systems. Flow control methods are required to avoid these negative effects. In the recent two decades the flow control by means of air-jet vortex generators has been also intensively investigated. In this method a streamwise vortex is introduced by an oblique jet. The necessity to supply air by a pipe system may be considered a disadvantage. In order to eliminate this feature, it has been proposed to put out a rod instead of a jet. It has been shown that the application of a rod can introduce the same effect as a jet, as long as the streamwise vortex generation is concerned and appropriate dimensions are used. The present paper focuses on the influence of rod vortex generators on a flow pattern downstream. The results presented here concern experimental and numerical investigations and provide guidelines for the design of a new flow control method dedicated mainly to external flows.

关键词： Air-jet vortex generator Boundary layer Flow control Rod vortex generator Streamwise vortices

Hexagonal warping effect on Majorana zero modes at the ends of superconducting vortex lines in doped strong 3D topological insulators

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Science China(Physics,Mechanics & Astronomy) 2019年第11期62卷 125-134页

作者： Chuang Li Lun-Hui Hu Fu-Chun Zhang Department of Physics Zhejiang UniversityHangzhou 310027China Kavli Institute for Theoretical Sciences University of Chinese Academy of SciencesBeijing 100190China Department of Physics University of CaliforniaSan Diego CA 92093USA CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China

In a superconducting topological insulator, a superconducting vortex line can trap a one-dimensional topological band with localized Majorana zero modes at the ends. Here, we study the effect of hexagonal warping and its corresponding symmetry-breaking effect on vortex phase transition. We perform both analytical calculations based on a semiclassical formula and numerical calculations based on full quantum mechanics using the Bogoliubov-de Gennes equation. We find that the hexagonal warping term extends the topological region of the vortex line as the chemical potential changes and leads to MZMs, even in the absence of topological surface states.

关键词： topological insulator topological superconductor vortex phase transition Majorana zero modes hexagonal warping

Influence of Separated vortex on Aerodynamic Noise of an Airfoil Blade

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Journal of Thermal Science 2010年第1期19卷 60-66页

作者： Soichi Sasaki Hajime Takamatsu Masao Tsujino Haruhiro Tsubota Hidechito Hayashi Faculty of Engineering Nagasaki University1-14 Bunkyo-machiNagasaki 852-8521Japan Graduate School of Science and Technology Nagasaki University1-14 Bunkyo-machiNagasaki 852-8521Japan Research Division Komatsu Ltd.1200MandaHiratsuka-shiKanagawa 254-8567Japan

In order to clarify the mechanism by which aerodynamic noise is generated from separated flow around an airfoil blade,the relation between the attack angle and the aerodynamic noise of the blade was analyzed using a wind tunnel experiment and a CFD *** the case of rear surface separation,the separated vortex which has a large-scale structure in the direction of the blade chord is transformed into a structure that concentrates at the trailing edge with an increase in the attack *** aerodynamic noise level then becomes small according to the vortex scale in the blade *** the flow is separated at the leading edge,a separated vortex of low pressure is formed at the vicinity of the trailing *** pressure fluctuations on the blade surface at the vicinity of the trailing edge become large due to the vortex in the *** is considered that the aerodynamic noise level increases when the flow is separated at the leading edge because the separated vortex is causing the fluctuations due to wake vortex shedding.

关键词： vortex Aerodynamic Noise Shear Flow Separation Airfoil