共查询到20条相似文献,搜索用时 93 毫秒
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曹瑞 《纯粹数学与应用数学》2012,(1):92-98
对一类带色散项的高阶非线性Schrdinger方程的精确解进行研究.通过行波约化,将一类带色散项的高阶非线性Schrdinger方程化为一个高阶非线性常微分方程.再借助于计算机代数系统Mathematica通过构造非线性常微分方程的精确解,成功获得了一系列含有多个参数的包络型精确解,当精确解中参数取特殊值时可以得到两种新型的复合孤子解.并讨论了这两种孤子解存在的参数条件. 相似文献
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给出了一种改进的截断展开法,利用此方法借助于计算机符号计算求得了Burgers方程和浅水长波近似方程组的精确解,其中包括孤子解,并讨论其具体应用.改进后的方法与以前的方法相比能得到方程的更多形式的精确解.所给出的改进的截断展开法也可以用来研究其它非线性发展方程的孤子解,是求非线性发展方程精确解的一种有效的直接方法. 相似文献
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研究了两种改善风力机叶型气动性能的流动控制技术,分别对风力机专用S809翼型和较大升阻比的FX 60-100翼型进行应用研究.首先,通过在叶型前缘加装流动偏转器,研究流动偏转器对叶型流动分离的控制效果.并采用多岛基因算法,对流动偏转器进行多参数优化.结果表明:流动偏转器可以有效控制叶型的失速特性,推迟失速攻角和增加升力;基因优化算法能更大地提升流动偏转器的控制效果.其次,基于对风力机叶尖旋涡和尾涡特征以及叶片表面压力分布的分析,在叶片尖部加装不同倾斜角的旋涡扩散器控制叶尖涡.结果表明:涡扩散器能够提高叶尖涡涡核的总压,削弱其旋涡强度,使风力机尾流旋涡耗散更快,从而可以减小噪声,提高叶片效率. 相似文献
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该文定义了一个再生核空间W_2~2(*),在其中讨论了积分-微分方程解的存在唯一性,给出了积分-微分方程一个定解问题的精确解的表达式及由精确解得出近似解的性质. 相似文献
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研究了一类带Markov状态转换的跳扩散方程的数值解的问题,为讨论这类方程精确解的数值计算问题,我们给出了一种基于Euler格式的方程解的跳适应算法,并在一定的条件下,证明了基于这种新的跳适应算法所得到的方程的数值解是收敛于它的精确解,同时还给出了数值解收敛到其精确解的收敛阶数.最后,本文通过两个例子说明了这种跳适应算法的计算有效性. 相似文献
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二维RLW方程和二维SRLW方程的显式精确解 总被引:2,自引:0,他引:2
本文讨论了二维RLW方程和二维SRLW方程孤立波解的性态,通过直接积分的方法求出了这两个方程的显式精确孤立波解,并通过选取初始条件的方法求出了二维RLW方程和二维SRLW方程的另一类精确行波解. 相似文献
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In theoretical ways to solve the N-S equation, we will confront many difficulties. For example, the complex mathematical calculation, the 3D velocity components and the nonlinear terms, etc. We find that from the basis of Stokes-Helmholtz decomposition and after some processing, we can get a method of constructing the vortex superposition solutions. We get a set of exact solutions in different coordinates and we hope these solutions will be helpful to a clearer understanding of the vortex in Fluid Mechanics. 相似文献
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Joseph Majdalani Sjoerd W. Rienstra 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2007,58(2):289-308
The bidirectional vortex refers to the bipolar, coaxial swirling motion that can be triggered, for example, in cyclone separators
and some liquid rocket engines with tangential aft-end injectors. In this study, we present an exact solution to describe
the corresponding bulk motion in spherical coordinates. To do so, we examine both linear and nonlinear solutions of the momentum
and vorticity transport equations in spherical coordinates. The assumption will be that of steady, incompressible, inviscid,
rotational, and axisymmetric flow. We further relate the vorticity to some power of the stream function. At the outset, three
possible types of similarity solutions are shown to fulfill the momentum equation. While the first type is incapable of satisfying
the conditions for the bidirectional vortex, it can be used to accommodate other physical settings such as Hill’s vortex.
This case is illustrated in the context of inviscid flow over a sphere. The second leads to a closed-form analytical expression
that satisfies the boundary conditions for the bidirectional vortex in a straight cylinder. The third type is more general
and provides multiple solutions. The spherical bidirectional vortex is derived using separation of variables and the method
of variation of parameters. The three-pronged analysis presented here increases our repertoire of general mean flow solutions
that rarely appear in spherical geometry. It is hoped that these special forms will permit extending the current approach
to other complex fluid motions that are easier to capture using spherical coordinates. 相似文献
13.
Olga S. Rozanova Jui-Ling Yu Chin-Kun Hu 《Nonlinear Analysis: Real World Applications》2012,13(4):1941-1954
As a continuation of our work, Rozanova et al. (2010) [1] we study possible trajectories of a long time existing vortex in a model of the atmosphere dynamics, where the vortex can be interpreted as a tropical cyclone. The model can be obtained from the system of primitive equations governing the motion of air over the Earth’s surface after averaging over the height. We consider approximations of l-plane and β-plane used in geophysics for modeling of middle scale processes and equations on the whole sphere as well. We associate with a cyclone a special class of smooth solutions having a form of a localized steady non-singular vortex moving with a bearing field. We show that the solutions satisfy the equations of the model either exactly or with a discrepancy which is small in a neighborhood of the trajectory of the center of vortex. We show both analytically and numerically that the trajectory of a localized vortex keeps the features of trajectory of vortex with a linear profile of velocity, where the exact solution can be obtained. 相似文献
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Stefan G. Llewellyn Smith Y. Hattori 《Communications in Nonlinear Science & Numerical Simulation》2012,17(5):2101-2107
New solutions for compact vortex rings and vortices in the presence of swirl and toroidal magnetic field are presented. Steady solutions are found for thin-core vortex rings, generalizing the classical results of Kelvin and Hicks. An exact family of steady spherical solutions is found in the case when the underlying governing equation, originally due to Hicks, is linear. Proper matching of the pressure is critical in obtaining these solutions, for which another 19th century equation proves key. Contour dynamics simulations show the existence of counter-propagating dipolar structures when both swirl and magnetic fields are present. 相似文献
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Doklady Mathematics - Classes of exact solutions corresponding to vortex and potential flows are presented within the framework of a hydrodynamic model describing flows of a viscous incompressible... 相似文献
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讨论了带有热源项的非线性扩散方程.通过一种直接简洁的方法得到了几种精确解.该方法可用于更高阶演化方程的求解问题. 相似文献
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考虑边界层低涡为受非绝热加热和摩擦强迫并满足热成风平衡的轴对称涡旋系统,采用Boussinesq近似,通过求解柱坐标系中涡旋模式的初值问题,分析了热源强迫对低涡流场结构的影响.结果表明:热源强迫对低涡的流场结构有重要影响,并且这种影响的具体表现形式与加热的径向分布有密切关系.对边界层涡旋解讨论的结果可以解释青藏高原低涡系统的某些重要结构特征. 相似文献
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We discuss the interaction between point vortices and point dipole vortices in two-dimensional ideal hydrodynamics and show
that the equations of motion of the interacting point and point dipole vortices are exactly integrable. We find exact solutions
for all possible parameter values characterizing the vortices and for arbitrary initial conditions and establish the regimes
of vortex motion. 相似文献
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This paper is concerned with the exact analytic solutions for the velocity field and the associated tangential stress corresponding to a potential vortex for a fractional Maxwell fluid. The fractional calculus approach is taken into account in the constitutive relationship of a non-Newtonian fluid model. Exact analytic solutions are obtained by using the Hankel transform and the discrete Laplace transform of sequential fractional derivatives. The solutions for a Maxwell fluid appear as the limiting cases of our general solutions by setting α=1. The influence of fractional coefficient on the decay of vortex velocity is also analyzed by graphical illustrations. 相似文献
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二维色散长波方程组的精确解 总被引:2,自引:0,他引:2
利用齐次平衡法给出了二维色散长波方程组的定态解、孤立波解与非孤立波解等几种显式精确解。这个方法也可用来寻找其它非线性发展方程的不同类型的精确解。 相似文献