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1.
We study and characterise the breather-induced quantised superfluid vortex filaments which correspond to the Kuznetsov-Ma breather and super-regular breather excitations developing from localised perturbations. Such vortex filaments, emerging from an otherwise perturbed helical vortex, exhibit intriguing loop structures corresponding to the large amplitude of breathers due to the dual action of bending and twisting of the vortex. The loop induced by the Kuznetsov-Ma breather emerges periodically as time increases, while the loop structure triggered by the super-regular breather—the loop pair—exhibits striking symmetry breaking due to the broken reflection symmetry of the group velocities of the super-regular breather. In particular, we identify explicitly the generation conditions of these loop excitations by introducing a physical quantity—the integral of the relative quadratic curvature—which corresponds to the effective energy of breathers. Despite the nature of nonlinearity, it is demonstrated that this physical quantity shows a linear correlation with the loop size. These results will deepen our understanding of breather-induced vortex filaments and be helpful for controllable ring-like excitations on the vortices. 相似文献
2.
The solutions of the intensity envelopes of a novel type of incoherently coupled spatial soliton pair, named anti-dark soliton pair, are deduced by careful theoretical analyses. Simultaneously the forming conditions of the anti-dark soliton pair are derived in the paper, according to which an example of anti-dark soliton family that exists in cubic-quintic nonlinear media is given. 相似文献
3.
Min Li Bo Tian Wen-Jun Liu Yan Jiang Kun Sun 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,59(2):279-289
Coupled modified nonlinear Schr?dinger (CMNLS) equations
describe the pulse propagation in the picosecond or femtosecond
regime of the birefringent optical fibers. A new type of the Lax
pair and another hierarchy of the infinitely many conservation laws
are derived based on the Wadati-Konno-Ichikawa system. By means of
the Hirota method, soliton solutions in the normal dispersion regime
are obtained. Parametric regions for the existence of dark and
anti-dark vector soliton solutions are given. Asymptotic analysis
shows that the collision between two solitons (two anti-dark
solitons, two dark solitons, or dark and anti-dark solitons) in each
polarization direction is elastic. Moreover, there is no energy
transfer between two polarization components of each vector soliton,
whether dark or anti-dark vector soliton. In addition, dark and
anti-dark solitons can coexist on the same background seen from the
collision between the dark and anti-dark solitons in one
polarization direction. Our graphical analysis shows that the
parameters in the CMNLS equations not only determine the regions for
the existence of dark and anti-dark soliton solutions but also
control the phase and direction of the propagation of the solitons.
Finally, through the linear stability analysis, the modulational
instability condition is given. 相似文献
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6.
J. C. Liang Z. B. Cai Y. Z. Sun L. Yi H. C. Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(3):685-689
In this paper we answer the question: “what types of
spatial soliton can be formed based on two-photon-isomerisation (TPI)”. The
conclusion that anti-dark solitons are not supported by monotonic
nonlinearity should cast light on the notion of fundamental spatial
solitons. The idea to obtain a bright TPI soliton with the joining of a
background light or with the coupling of a dark soliton offers new schemes
of light-controlling-light. 相似文献
7.
Asymmetric W-shaped and M-shaped soliton pulse generated from a weak modulation in an exponential dispersion decreasing fiber
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We study localized waves on continuous wave background in an exponential dispersion decreasing fiber with two orthogonal polarization states. We demonstrate that asymmetric W-shaped and M-shaped soliton pulse can be generated from a weak modulation on continuous wave background. The numerical simulation results indicate that the generated asymmetric soliton pulses are robust against small noise or perturbation. In particular, the asymmetric degree of the asymmetric soliton pulse can be effectively controlled by changing the relative frequency of the two components. This character can be used to generate other nonlinear localized waves, such as dark–antidark and antidark–dark soliton pulse pair, symmetric W-shaped and M-shaped soliton pulse. Furthermore, we find that the asymmetric soliton pulse possesses an asymmetric discontinuous spectrum. 相似文献
8.
采用粒子图像测速技术, 获得了不同环境压力下介质阻挡放电等离子体诱导流场启动涡随时间的演化规律和诱导流场分布的变化规律. 实验表明: 不同环境压力下, 诱导流场都会出现启动涡, 压力较高, 启动涡逐渐向右即向植入电极一侧扩散并最终消失, 扩散速度随时间递减, 压力较小, 诱导漩涡不会随放电时间的增大而消失; 环境压力减小, 等离子体诱导流场的启动时间减小, 诱导流场的法向分量增强、横向分量减弱, 诱导流线形状的变化规律是:L→U→V, L 型流线没有诱导漩涡, U 型流线有两个诱导旋涡, 分别分布在U 型凹槽和右侧, V 型流线有一个诱导漩涡, 分布在V 中间.
关键词:
介质阻挡放电
诱导流场
启动涡
演化 相似文献
9.
Solitary Wave Evolution of Optical Planar Vortices in Self-Defocusing Photorefractive Media
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Solitary wave evolution of optical planar vortices in isotropie self-defoeusing photorefractive media is investigated in detail. We demonstrate that the formation of a planar vortex soliton intensively depends on the diameter and maximum intensity of the input vortex Seam. The exact solutions of planar vortex solitons are obtained due to the Petviashvili iteration method. It is found that, with the increasing soliton maximum intensity, the soliton core will be gradually diminished to a minimum value. 相似文献
10.
A flow induced by a rotating disk mounted at the top of a cubic container totally filled with a liquid is studied experimentally.
The flow pattern is visualized for Reynolds numbers in the interval 1500–6000, and the velocity variation along the axis of
the container, which coincides with the axis of revolution of the disk, is observed by means of Doppler laser anemometry (DLA).
As Re grows, the velocity axial component starts fluctuating because of the vortex core precession. The breakdown of the vortex
helical structure becomes pronounced at Re>4000 without the formation of the return flow region (vortex breakdown bubble)
at the axis. With the Reynolds number and the container height-to-disk radius ratio being the same, the axial flow patterns
in standard cylindrical [1] and cubic containers differ radically. In the latter vessel at low Re, the steady flow regime
and axisymmetric bubble breakdown of the vortex structure near the axis are absent. 相似文献
11.
Kivshar YS Nepomnyashchy A Tikhonenko V Christou J Luther-Davies B 《Optics letters》2000,25(2):123-125
We study the interaction of an optical vortex soliton with a dark-soliton stripe in a bulk nonlinear defocusing medium. We develop a multiscale asymptotic theory to predict the main effect of the interaction and then study it experimentally, observing vortex-induced stripe bending, development of the transverse instability, and stripe breakup. 相似文献
12.
We present the observation of incoherent anti-dark photovoltaic solitons in LiNbO3:Fe crystal. This new class of soliton states involves bright photovoltaic solitons on a background beam meeting ?? > 1, where ?? is the ratio of background illumination photovoltaic constant to that of soliton beam. For ?? < 1, dark photovoltaic solitons are generated. Furthermore, this novel type solitons are investigated experimentally by injecting coherent light and partially coherent background of infinite extent. In case of spatial coherence of the background lower than the threshold of incoherent modulation instability, these results indicate that bright photovoltaic solitons can propagate in a stable fashion. 相似文献
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14.
The effect of a vortex in a gas flow on an air-blast arc is investigated. The radial density of a vortex in the compressible flow is evaluated with a simple model. The experiments show that the width of a low pressure channel on the axis of the nozzle is comparable to the theoretical values. The measured electric field strength profile is strongly influenced by the presence of such a vortex. In addition, the thermal interrupting capability is drastically lowered by vortex superimposed on the axial gas flow. 相似文献
15.
本文采用Navier-Stokes方程和Spalart-Allmaras湍流模型,对只在叶轮尾缘带有导流罩的低压轴流风扇进行了三维稳态内流模拟,详细分析了叶顶流场中叶尖涡的产生和发展轨迹。研究结果表明,叶尖涡在距叶尖前缘约1/4叶顶轴向弦长的吸力面附近形成,在叶轮出口附近消失,在切向约占3/4流道,近似形成一个涡环,阻塞主流.在回转面上,叶尖涡涡核先沿流线方向发展,在导流罩附近逐渐转为切向方向发展;在径向方向,叶尖涡先沿外径方向发展,在导流罩附近转向内径方向移动。空调室外机系统的不对称结构引起叶尖涡在叶轮旋转过程中的相对位移.流量的变化对叶尖涡的轴向位置影响较大,而对其径向位置的影响不明显;小流量时叶尖涡的轴向移动能力减弱,切向移动能力增强,消失位置向前缘方向移动. 相似文献
16.
Gulevich DR Kusmartsev FV Savel'ev S Yampol'skii VA Nori F 《Physical review letters》2008,101(12):127002
We predict a new class of excitations propagating along a Josephson vortex in two-dimensional Josephson junctions. These excitations are associated with the distortion of a Josephson vortex line and have an analogy with shear waves in solid mechanics. Their shapes can have an arbitrary profile, which is retained when propagating. We derive a universal analytical expression for the energy of arbitrary shape excitations, investigate their influence on the dynamics of a vortex line, and discuss conditions where such excitations can be created. Finally, we show that such excitations play the role of a clock for a relativistically moving Josephson vortex and suggest an experiment to measure a time dilation effect analogous to that in special relativity. 相似文献
17.
轴流式涡流管内三维流场的大涡模拟 总被引:1,自引:0,他引:1
根据涡流管内可压缩气体的强旋转运动是导致涡流管能量分离的根本原因,提出了在涡流管内加入一个"X"型导流片迫使气流产生强旋转运动,使其进气方式变为轴流式。利用计算流体动力学(CFD)的方法,建立了轴流式和切流式涡流管内部气体流动的三维大涡数值模型,对其内部气流流场进行了数值模拟。数值模拟结果表明:"X"型导流片可以改变轴向进入气体的运动方向,使气体产生高速旋转运动,得出"X"型导流片的叶片夹角为θ=120°时,气体的旋转效果最好;大涡模拟可以较好地模拟涡流管内气流的三维流场。 相似文献
18.
In the previous Letter (Zheng C L and Zhang J F 2002 Chin. Phys. Lett. 19 1399), a localized excitation of the generalized Ablowitz-Kaup-Newell-Segur (GAKNS) system was obtained via the standard Painlevé truncated expansion and a special variable separation approach. In this work, starting from a new variable separation approach, a more general variable separation excitation of this system is derived. The abundance of the localized coherent soliton excitations like dromions, lumps, rings, peakons and oscillating soliton excitations can be constructed by introducing appropriate lower-dimensional soliton patterns. Meanwhile we discuss two kinds of interactions of solitons. One is the interaction between the travelling peakon type soliton excitations, which is not completely elastic. The other is the interaction between the travelling ring type soliton excitations, which is completely elastic. 相似文献
19.
利用强非局域非线性介质中傍轴光束传输的修正Snyder-Mitchell模型讨论了两束共线(即光束中心和传输方向都相同)拉盖尔-高斯型光孤子(CLGS)构成的涡旋光孤子传输过程。在一定条件下,涡旋光束在传输过程中,光束截面光斑发生旋转现象,但光束的束宽保持不变,称之为旋转涡旋光孤子。涡旋光孤子旋转的现象可以通过叠加光场中的古依相位来解释。结果展现了几个旋转涡旋光孤子在传输过程中的旋转现象和强非局域介质中多环形旋转涡旋光孤子的传输。 相似文献