共查询到20条相似文献,搜索用时 31 毫秒
1.
Ying Chen Jia-fu Lin Qun Lin 《计算数学(英文版)》2002,20(4):429-436
AbstractFor the first order nonstationary hyperbolic equation taking the piecewise linear discontinuous Galerkin solver, we prove that under the uniform rectangular partition, such a discontinuous solver, after postprossesing, can have two and half approximative order which is half order higher than the optimal estimate by Lesaint and Raviart under the rectangular partition. 相似文献
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CONVERGENCE OF THE LAX-FRIEDRICHS SCHEME AND STABILITY FOR CONSERVATION LAWS WITH A DISCONTINUOUS SPACE-TIME DEPENDENT FLUX 总被引:4,自引:0,他引:4 下载免费PDF全文
The authors give the first convergence proof for the Lax-Friedrichs finite differencescheme for non-convex genuinely nonlinear scalar conservation laws of the formu_t f(k(x, t), u)_x = 0,where the coefficient k(x, t) is allowed to be discontinuous along curves in the (x, t)plane. In contrast to most of the existing literature on problems with discontinuouscoefficients, here the convergence proof is not based on the singular mapping approach,but rather on the div-curl lemma (but not the Young measure) and a Lax type en-tropy estimate that is robust with respect to the regularity of k(x, t). Following [14],the authors propose a definition of entropy solution that extends the classical Kruzkovdefinition to the situation where k(x, t) is piecewise Lipschitz continuous in the (x, t)plane, and prove the stability (uniqueness) of such entropy solutions, provided that theflux function satisfies a so-called crossng condition, and that strong traces of the solu-tion exist along the curves where k(x, t) is disco 相似文献
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一维高精度离散GDQ方法 总被引:4,自引:0,他引:4
GDQ method is a kind of high order accurate numerical methods developed several years ago, which have been successfully used to simulate the solution of smooth engineering problems such as structure mechanics and incompressible fluid dynamics. In this paper, extending the traditional GDQ method, we develop a new kind of discontinuous GDQ methods to solve compressible flow problems of which solutions may be discontinuous. In order to capture the local features of fluid flows, firstly, the computational domain is divided into many small pieces of subdomains. Then, in each small subdomain, the GDQ method is implementedand some kinds of numerical flux limitation conditions will be required to keep the correct flow direction. At the boundary interface between subdomains, we also use some kind of flux conditions according to the flow direction. The numerical method obtained by the above steps has the advantages of high order accuracy and easy to treat boundary conditions. It can simulate perfectly nonlinear waves such as shock, rarefaction wave and contact discontinuity. Finally, the numerical experiments on one dimensional Burgers equation and Euler equations are given.The numerical results verify the validation of the method. 相似文献
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We study the Cauchy problems for the isentropic 2-d Euler system with discontinuous initial data along a smooth curve. All three singularities are present in the solution: shock wave, rarefaction wave and contact discontinuity. We show that the usual restrictive high order compatibility conditions for the initial data are automatically satisfied. The local existence of piecewise smooth solution containing all three waves is established. 相似文献
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本文论讨单连通区域上一阶线性混合型(椭圆—双曲型)方程组的间断边值问题.我们首先给出混合型方程组特别是最简单的混合型方程组解的表示式,然后使用逐次逼近法,证明上述边值问题解的存在性与唯一性.由以上结果,可导出A.V.Bitsadze所得的Lavrent’ev-Bitsadze方程u 相似文献
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《Applied Numerical Mathematics》2006,56(3-4):444-458
We use an artificial viscosity term to stabilize discontinuous Galerkin solutions of hyperbolic conservation laws in the presence of discontinuities. Viscous coefficients are selected to minimize spurious oscillations when a kinematic wave equation is subjected to piecewise constant initial data. The same strategy is used with a local linearization in more complex situations. Several one and two-dimensional flow problems illustrate performance. A shock detection scheme [L. Krivodonova, J. Xin, J.-F. Remacle, N. Chevaugeon, J.E. Flaherty, Shock detection and limiting with discontinuous Galerkin methods for hyperbolic conservation laws, Appl. Numer. Math. 48 (2004) 323–338] further sharpens results near discontinuities. 相似文献
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关于一类非连续的正交函数及其应用的探讨 总被引:4,自引:0,他引:4
齐东旭 《高校应用数学学报(A辑)》1990,5(1):39-46
本文研究一类新的非连续分段线性函数系,它是正交且完备的。特别讨论了它与离散斜变换的内在联系,从而建立直接的快速算法。分析表明这些结果有希望作为数字信号处理某些问题的新的有效的数学工具。 相似文献
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1Formulati0nofDiscontinuousBoundaryValueProblemsLetDbeanN 1-connectedb0undeddomaininthez=x iy-planeCwiththeboundaryFEC:(0相似文献
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一阶双曲问题的有限元后验误差估计至今没有得到很好的解决.本文对d维区域上一阶双曲问题的k次间断有限元逼近提出了一种新的后验误差分析方法, 进而建立了间断有限元解在DG范数下(强于L2范数)基于误差余量型的后验误差估计. 数值计算验证了本文理论分析的有效性. 本文方法也适用于其他变分问题有限元逼近的后验误差分析. 相似文献
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本文通过建立一个比较结果.应用不动点定理讨论了Banach空间含间断项的一阶混合型微分一积分方程终直问题的最大解和最小解的存在性.推广改进了某些文献中的相应结果. 相似文献
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邵志强 《Annals of Differential Equations》2004,20(1):70-76
This paper studies the initial boundary problems for semilinear strictly hyperbolic second-order equations with discontinuous data. Under the uniform Lopatinski boundary condition, the local existence theorem of discontinuous solutions and the structure of singularities of the solutions are obtained. 相似文献
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In this paper, we are concerned with the local structural stability of one-dimensional shock waves in radiation hydrodynamics described by the isentropic Euler-Boltzmann equations. Even though in this radiation hydrodynamics model, the radiative effects can be understood as source terms to the isentropic Euler equations of hydrodynamics, in general the radiation field has singularities propagated in an angular domain issuing from the initial point across which the density is discontinuous. This is the major difficulty in the stability analysis of shocks. Under certain assumptions on the radiation parameters, we show there exists a local weak solution to the initial value problem of the one dimensional Euler-Boltzmann equations, in which the radiation intensity is continuous, while the density and velocity are piecewise Lipschitz continuous with a strong discontinuity representing the shock-front. The existence of such a solution indicates that shock waves are structurally stable, at least local in time, in radiation hydrodynamics. 相似文献
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《数学物理学报(B辑英文版)》2017,(6)
This paper deals with the existence and the asymptotic behavior of discontinuous traveling wave entropy solutions for a modified Allen-Cahn model,in which,the usual Ficken-based model for phase transition is replaced with a more physical model with nonlinear diffusive flux. The discontinuous traveling waves correspond to the discontinuous phase transition phenomena. 相似文献
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The autors apply the result obtained in [1] to consider a class of discontinuous piston problems for the system of one dimensional isentropic flow and prove that this problem admits a unique global classical discontinuous solution only containing one shock. 相似文献
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Global Perturbation of the Riemann Problem for the System of Compressible Flow Through Porous Media 下载免费PDF全文
In this paper we consider the unperturbatcd and perturbated Riemann problem for the damped quasiliuear hyperbolic system {v_t - u_x = 0 u_t + p(v)_x = -αu, α > 0, p'(v} < 0 with initial structure of two rarefaction waves or one rarefaction wave plus one shock wave. Under certain restrictions, it admits a unique global discontinuous solution in a class of piecewise continuous and piecewise smooth functions and keeps the initial structure. Moreover, the shock strength is found decaying exponentially due to damping for the later case. 相似文献
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1IntroductionAs we well know,the study of the local existence of discontinuous solutions to semilinearor quasi-linear hyperbolic systems in higher dimension spaces has attracted considerable at-tention of many well-known mathematicians,thanks to A.Majda’… 相似文献
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Liu Zhenhai 《系统科学与数学》2000,13(1)
In this paper we shall consider a discontinuous nonlinear nonmonotone elliptic boundary value problem, i.e. a quasilinear elliptic hemivariational inequality. This kind of problems is strongly motivated by various problems in mechanics. By use of the notion of the generalized gradient of Clarke and the theory of pseudomonotone operators, we will prove the existence of solutions. 相似文献
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一类四阶抛物型积分-微分方程的混合间断时空有限元法 总被引:2,自引:1,他引:1
构造四阶抛物型积分-微分方程的混合间断时空有限元格式,利用混合有限元方法将高阶方程降阶,利用空间连续而时间允许间断的时空有限元方法离散方程,证明离散解的稳定性,存在唯一性和收敛性. 相似文献