BOUNDARY AND CORNER LAYER BEHAVIOR IN SINGULARLY PERTURBED ROBIN BOUNDARY VALUE PROBLEM

This paper is concerned with boundary and corner layer behavior of the singularly perturbed Robin boundary value problem(RP) for the second-order nonlinear differential equations. The existence and asymptotic estimate of solutions of (RP) is discussed by appropriately constructing the bounding functions and using the theory of differential inequality.     

Lattice Bhatnagar-Gross-Krook Simulations of Hydromagnetic Double-Diffusive Convection in a Rectangular Enclosure with Opposing Temperature and Concentration Gradients

The temperature-concentration lattice Bhatnagar-Gross-Krook （TCLBGK） model with a robust boundary scheme is developed for two-dimensional hydromagnetic double-diffusive convective flow of a binary gas mixture in a rectangular enclosure, in which the upper and lower walls are insulated, while the left and right walls are constant temperature and constant concentration, and a uniform magnetic field is applied in the x-direction. In the model the velocity, temperature and concentration fields are solved by three independent LBGK equations, which are combined into a coupled equation for the whole system. In our simulations, we take the Prandtl number Pr = 1.0, the Lewis number Le = 2.0, the thermal Rayleigh number RaT = 10^5, and the aspect ratio A = 2 for the enclosure. The numerical results are found to be in good agreement with those of previous studies.     

STEFAN PROBLEM WITH NONLINEAR BOUNDARY FLUX AND INTERNAL CONVECTION OF A MATERIAL

A Stefan problem with nonlinear boundary flux and internal convection of a material are considered. The existence, uniqueness and continuous dependence of globally weak solution of this problem are obtained. This paper extends the results of Fahuai Yi and T.M.Shih, relaxes restrictions that does not be to accord with reality very much on internal convection and boundary conditions in their articles.     

薄层流中的一类三阶奇摄动边值问题的渐近分析

本文研究薄层流中出现的一类三阶奇摄动数学模型．本文不采用研究其渐近等价的二阶奇摄动微分方程的方法,而利用边界层函数法,直接讨论该数学模型的渐近解,并严格地证明了解的存在唯一性和其渐近解的一致有效性．本文的结果不仅去掉了以往方法所必须的位势条件,纠正了某个不适定的假设,而且推广了以往的结果．     

平板边界层转捩过程中低频信号的产生

利用Fourier频谱分析和小波变换处理在平板边界层转捩过程中测得的速度信号,观察到频谱中存在低于基本扰动波频率的含能信号,即文中所谓的低频信号.在进一步分析中,发现这种低频信号的产生可能与流动的间歇性有关.由于流动的间歇性导致速度信号的脉动,数据结构产生间歇变化,这种信号并不一定对应于流场中的某一物理结构的真实频率 关键词： 边界层 转捩 Fourier频谱分析 小波变换     

确定地下水污染强度的反问题方法

探讨了山东省淄博市张店区沣水南部区域地下水的硫酸污染问题 .根据观测井点的浓度数据 ,将硫酸污染强度的识别问题作为一个已知终值数据的源项反问题 .应用积分恒等式方法分析了未知源函数与已知数据间的数据相容性 ,进而基于最优化策略进行了数据反演 ,计算结果与实际估计值基本吻合     

IMPLICIT DIFFERENCE APPROXIMATION FOR A TIME FRACTIONAL ADVECTION-DISPERSION EQUATION

In this paper, a time fractional advection-dispersion equation is considered. From the relationship between the Caputo derivative and the Grunwald derivative, the Caputo derivative is approximated by using the Griinwald derivative. An implicit difference approximation for this equation is proposed. We prove that this approximation is unconditionally stable and convergent. Finally, numerical examples are given.     

具有转向点的一类奇摄动边值问题解的多重边界层现象

本文讨论如下边值问题：x=0是转向点（c（0）=0），而在x=－1处出现多重边界层现象．对不同层次采用不同的伸长变量，构造具有不同量级的边界层校正项，得到关于解的一致有效的渐近展开式和有关的余项估计．     

多水平方法在二维山丘地形大气污染物扩散的数值模式的应用

对海风热力内边界层模式稍作修改后，不仅可模拟海风流场，也可以模拟河谷中的风场。在模拟河谷地区风场的实例计算中，数值计算结果和实测值基本符合。将多水平方法中用多最多的ＰＣＧ方法（预条件共轭梯度法）用来数值解由海风热力内边界层模式离散后得到的线代数方程组，节省了计算时间。     

一类非线性方程的激波解

该文是利用匹配条件讨论一类非线性方程激波解。得出了对应的激波解与边界条件的关系。