两参数奇异摄动非线性双曲型微分系统的过渡冲击层广义解

研究了一类两参数双曲型微分系统奇异摄动初始边值问题.首先,利用奇异摄动理论和方法,注意到两个小参数,构造了问题的外部解.其次,利用多重尺度变量和伸长变量,分别得到了原问题解的过渡冲击层、边界层和初始层校正项.最后,得到了原问题解的渐近展开式,并利用泛函分析不动点理论,证明了渐近解的一致有效性.由本方法求得的原问题的渐近解,它还可以进行微分,积分等解析运算,从而能了解相应过渡冲击层解的更进一步的性态.因此本方法具有良好的应用前景.     

一类边界层位置转移的非线性奇摄动问题

利用匹配渐近展开法,讨论了一类边界层位置转移的非线性奇摄动边值问题,并且通过对参数的五种不同取值的分类探讨,得到了该问题具有左边界层、右边界层或内部层之一的结论(其中左、右边界层又各分为两种类型).进而给出了该问题解的一致有效的零次渐近解,推广并改进了已有的结果.     

一类非线性奇摄动Dirichlet边值问题的匹配解法

利用匹配渐近展开法,讨论一类形如εy″+(xn-k)(y′+ym)=0的非线性奇摄动方程的Dirichlet边值问题,并且通过对参数k的五种不同取值的分类探讨,得到了该问题必有左边界层、右边界层或内部层之一的结论(其中左、右边界层又各分为两种类型).进而给出该问题解的零次渐近展开式,推广并改进了已有的结果.     

两参数非线性反应扩散积分微分方程的内层激波渐近解

研究了一类两参数非线性反应扩散积分微分奇摄动问题.利用奇摄动方法,构造了问题的外部解、内部激波层、边界层及初始层校正项,由此得到了问题解的形式渐近展开式.最后利用积分微分方程的比较定理证明了该问题解的渐近展开式的一致有效性.     

一类分数阶微分方程初值问题的奇摄动

研究了一类非线性分数阶微分方程加权初值问题的奇异摄动.在适当的条件下,首先求出了原问题的外部解,然后利用边界层函数法构造出解的初始层项,并由此得到解的形式渐近展开式,最后利用微分不等式理论,讨论了问题解的渐近性态,得到了原问题解的一致有效的渐近估计式.     

一类奇摄动燃烧ROBIN问题解的渐近性态

讨论了一类奇摄动燃烧问题.利用伸长变量,构造了问题解的边界层和内部层,并且得到了形式渐近解.再利用微分不等式证明了解的一致有效性.     

具有快慢层的非光滑奇异摄动问题的空间对照结构

该文研究了具有快慢层的非光滑奇异摄动问题的空间对照结构.利用边界层函数法构造了该问题的形式渐近解,并运用"缝接法"证明了问题光滑解的存在性以及渐近解的一致有效性.最后,通过例子验证了所得结果的有效性.     

具有转向点的二阶非线性方程Robin问题的奇摄动

本文应用微２发不等式的方法，研究了盯有转向点的二阶非线性方程Ｒｏｂｉｎ问题的奇摄动，根据ｆｙ在转向点附近的性态，边值问题的解将呈现冲击层现象和边界层现象。在适当的假设条件下，我们证明了该问题解的存在性和不同的渐近性质。     

一类非线性奇摄动反应扩散问题的广义内部冲出层解[英文]

研究了一类广义奇摄动反应扩散问题. 在适当的假设下, 首先得到了退化问的广义解,然后利用广义函数理论构造了原问题的广义冲击层渐近解.再利用泛函分析不动点定理证明了具有广义内部冲击层的渐近解的一致有效性.     

一类四阶非线性奇摄动方程的边值问题

利用匹配渐近展开法,讨论了一类四阶非线性方程的具有两个边界层的奇摄动边值问题．引进伸长变量,根据边界条件与匹配原则,在一定的可解性条件下,给出了外部解和左右边界层附近的内层解,得到了该问题的二阶渐近解,并举例说明了这类非线性问题渐近解的存在性．     

BOUNDARY LAYER ASYMPTOTIC BEHAVIOR OF INCOMPRESSIBLE NAVIER-STOKES EQUATION IN A CYLINDER WITH SMALL VISCOSITY

The object of this article is to study the boundary layer appearing at large Reynolds number （small viscosity ε） incompressible Navier Stokes Equation in a cylinder in space dimension three. These are Navier-Stokes equations linearized around a fixed velocity flow： the authors study the convergence as ε →0 to the inviscid type equations, the authors define the correctors needed to resolve the boundary layer and obtain convergence results valid up to the boundary and the authors also study the behavior of the boundary layer when, simultaneously, time and the Reynolds number tend to infinity, in which case the boundary layer tends to pervade the whole domain.     

一类非线性方程激波位置的转移

讨论一类非线性方程的激波位置，得出了在一定的情况下，当边界条件作微小的变化时，激波的位置将作较大的偏移，甚至由内层转到边界层。     

Solutions for the problem of boundary layer formation in a pseudo-plastic fluid: The case of gradual acceleration

We consider the development of the nonstationary boundary layer about a body that gradually starts to move in a resting fluid. Under certain conditions, we construct the solutions for the problem of formation of boundary layer in a pseudo-plastic fluid. The method used here is mainly based on a transformation which reduces the boundary layer system to a boundary value problem for a single quasilinear parabolic equation.     

Neumann and Robin problems in a cracked domain with jump conditions on cracks

The boundary value problem for the Laplace equation is studied on a domain with smooth compact boundary and with smooth internal cracks. The Neumann or the Robin condition is given on the boundary of the domain. The jump of the function and the jump of its normal derivative is prescribed on the cracks. The solution is looked for in the form of the sum of a single layer potential and a double layer potential. The solvability of the corresponding integral equation is determined and the explicit solution of this equation is given in the form of the Neumann series. Estimates for the absolute value of the solution of the boundary value problem and for the absolute value of the gradient of the solution are presented.     

THE INTERIOR LAYER SOLUTION TO NONLOCAL REACTION DIFFUSION EQUATIONS

An initial boundary value problem of semilinear nonlocal reaction diffusion equations is considered.Under some suitable conditions,using the asymptotic theory,the existence and asymptotic behavior of the interior layer solution to the initial boundary value problem are studied.     

On the global existence and uniqueness of solutions to the nonstationary boundary layer system

In this paper, we study the problem of boundary layer for nonstationary flows of viscous incompressible fluids. There are some open problems in the field of boundary layer. The method used here is mainly based on a transformation which reduces the boundary layer system to an initial-boundary value problem for a single quasilinear parabolic equation. We prove the existence of weak solutions to the modified nonstationary boundary layer system. Moreover, the stability and uniqueness of weak solutions are discussed.     

一类非线性边值问题激波位置的变动

在适当的条件下,利用奇摄动理论和引入调节函数的技巧讨论了一类非线性问题的激波位置．探讨了边界条件对于激波位置的影响．得出了当边界条件有微小变动时,激波位置将产生较大的变化,甚至改变激波位置的内部层或边界层属性．     

BOUNDARY LAYER ESTIMATION OF A SINGULAR PROBLEM WITH LIMIT EQUATION OF ORDER 2

ＢＯＵＮＤＡＲＹＬＡＹＥＲＥＳＴＩＭＡＴＩＯＮＯＦＡＳＩＮＧＵＬＡＲＰＲＯＢＬＥＭＷＩＴＨＬＩＭＩＴＥＱＵＡＴＩＯＮＯＦＯＲＤＥＲ２ＨＥＣＨＥＮＧ（何成）ＺＨＡＮＧＷＥＩＴＡＯ（张维弢）（ＩｎｓｔｉｔｕｔｅｏｆＳｙｓｔｅｍｓＳｃｉｅｎｃｅ，Ｃｈｉｎｅ...     

一类非线性奇摄动问题激波位置的转移

用一个特殊而简单的方法来讨论一类非线性奇摄动问题的激波位置．得出了在一定的情况下,当边界条件作微小的变化时,激波的位置将作较大的偏移,甚至由内层转到边界层．     

On the dynamics in a transitional boundary layer

IntroductionIll 1883 Professor Osborne Reynolds published in Philosopl1ical Transactions of the RoyalSociety the outcomes of his flow visua1ization at Manchester. These had shown that whetherthe flow in a pipe was direct to sinuous (or, as nowadays we would say, laminar to turbulent)depended on its Reynolds number. Transition from Iaminar to turbuIent flow becomes animportant probIem i1l fluid mechanics, which has attracted the interest of investigators fOrmore than l00 years. The partic…