共查询到19条相似文献,搜索用时 109 毫秒
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一个求解双曲型守恒律方程的高分辨率GVC格式 总被引:1,自引:0,他引:1
朱庆勇 《高等学校计算数学学报》2000,22(2):169-174
1 引 言本文研究双曲型方程:ut+fx=0, t>0,-∞相似文献
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封建湖 《纯粹数学与应用数学》1996,12(2):12-16
研究了如何利用迎风格式的耗散性构造中心差分TVD格式的方法,给 相应的定理,构造出新的耗散表达式。新格式既保留了二阶中心差分格式灵活方便的优点,又吸收了迎风格式耗散项比较精细的特点,同时具有TVD性质,使得新格式具有较同的激波分辨率。 相似文献
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本文讨论双曲型守恒律方程的熵稳定格式.对于给定的熵对,格式所满足的熵条件中的数值熵通量是不唯一的.Tadmor的充分条件可以唯一地确定标量方程的熵守恒通量,但不能唯一确定方程组的熵守恒通量,却可以给出方程组的空间一阶精度的熵守恒格式.也讨论了在熵守恒通量上添加数值粘性得到的显式熵稳定格式需要满足的条件及常见的时间离散对熵守恒和熵稳定的影响. 相似文献
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双曲型守恒律方程组的Godunov格式中离散激波的渐近稳定性 总被引:1,自引:0,他引:1
应隆安 《高等学校计算数学学报》1999,21(4):319-332
1引言我们研究求解守恒律初值问题的Godunov格式,其中f:RN→RN,并且方程(1)是严格双曲型的.我们还假定 的特征值(),…,N()均为非零,并且每一个特征在Lax意义下或者是真正非线性的,或者是线性退化的.利用Majda和Ralston的一个结果[6],我们将证明离散行波激波的存在性,然后证明激波的渐近稳定性,也即,如果初值是激波的一个小的摄动,则当t→由Godunov格式得到的解趋于一个平移了的行波激波.在[10]中我们证明了对于Lax-Friedrichs格式的渐近稳定性,所用的加… 相似文献
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一类多空间变量双曲型守恒律高阶MmB格式的收敛性戴嘉尊,成娟(南京航空航天大学)CONVERGENCEOFACLASSOFHIGHORDERACCURATEMmBSCHEMESFORCONSERVATIONLAWSINSEVERALSPACEDIME... 相似文献
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构造二维双曲型方程完全守恒差分格式的一种方法 总被引:1,自引:0,他引:1
§1 许多物理过程(例如气动力学,激光等离子体相互作用,磁流体力学,基本粒子输运等)的数学模型均可写成偏导数形式的二维不定常偏微分方程组: 相似文献
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为了降低经典的三阶加权本质无振荡(WENO)格式的数值耗散,提出了一种新的三阶WENO格式的修正模板近似方法.改进了经典WENO-JS格式中各候选模板上数值通量的一阶多项式逼近,通过加入二次项使模板逼近达到三阶精度.计算了相应的候选通量,并且通过引入可调函数φ(x),使得新的格式具有ENO性质.最后给出了一系列数值算例,证明了该方法的有效性. 相似文献
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双曲型守恒律组的一类差分格式及其熵条件 总被引:1,自引:0,他引:1
其中u(x,t)=(u_1(x,t),…,u_m(x,t))~T,f(u(x,t))=(f_1(u(x,t)),…,f_m(u(x,t)))~T,f的Jacobian记为 A(u)=?f(u)/?u,具有m个实特征值λ_1(u)≤λ_2(u)≤… ≤λ_m(u)以及完备的古特征向量系{γ_k(u)}_k~m=1.对区域R~+={(x,t)|x∈(-∞,+∞),t∈ 相似文献
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1.IntroductionIn[1],JinandXinconstructedaclassofthelocalrelaxationapproximation--TheRelaxingSchemesforsystemsofnonlinearcollservationlawsorsinglenonlinearconservationlawson,dofi(u)~ ;ac~0,(1l)otMoxil=1zwithinitialdatau(0,x)~"o(x),x~(xl,...,-cd),byusingtheideaofthelocalrelaxationapproximation[1--4].Theschemeisobtainedinthefollowingway:firstalinearhyperbolicsystemwithastiffsourcetermisconstructedtoapproximatetheoriginalsystem(1.1)withasmalldissipativecorrection;Then,thenewlinearhyperbolicsyste… 相似文献
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Hua-zhong Tang Gerald Warnecke 《计算数学(英文版)》2006,24(2):121-140
This paper presents a class of high resolution local time step schemes for nonlinear hyperbolic conservation laws and the closely related convection-diffusion equations, by projecting the solution increments of the underlying partial differential equations (PDE) at each local time step. The main advantages are that they are of good consistency, and it is convenient to implement them. The schemes are L^∞ stable, satisfy a cell entropy inequality, and may be extended to the initial boundary value problem of general unsteady PDEs with higher-order spatial derivatives. The high resolution schemes are given by combining the reconstruction technique with a second order TVD Runge-Kutta scheme or a Lax-Wendroff type method, respectively.
The schemes are used to solve a linear convection-diffusion equation, the nonlinear inviscid Burgers' equation, the one- and two-dimensional compressible Euler equations, and the two-dimensional incompressible Navier-Stokes equations. The numerical results show that the schemes are of higher-order accuracy, and efficient in saving computational cost, especially, for the case of combining the present schemes with the adaptive mesh method [15]. The correct locations of the slow moving or stronger discontinuities are also obtained, although the schemes are slightly nonconservative. 相似文献
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Hua-zhong Tang 《计算数学(英文版)》2000,18(3):313-324
1. IntroductionIn [6], Jin and adn constructed a class of uPWind relaxing schemes for nonlinearconservation lawswith initial data u(0, x) ~ "o(x), x ~ (xl, ...t -cd), by using the idea of the local relaxation approximation [2,3,6,10].The relaxing scheme is obtained in the following way: A linear hyperbolic systemwith a stiff source term is first constructed to approximate the original equation (1.1)with a small dissipative correction. Then this linear hyperbolic system is solved easilyby und… 相似文献
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1.引言本文研究如下非线性刚性守恒律方程组的全隐式差分逼近. 方程(1.1)中的源项g(u,v)定义为 g(u,v)=v-(1-μ)f(u),(1.2)其中f是u的一个给定函数,δ是一个小正参数,称为松弛时间,μ是参数.方程组(1.1)频繁出现于粘弹性力学中. 在零松弛时间限(δ→0)下,从(1.1)可得到如下方程组该方程组通常称为“平衡”模型,而方程组(1.1)称为“非平衡”模型. 文中将假设μ满足 0< μ< 1,(1.4)以便保证拟稳定性条件[19,20]和次特征条件[11,2,3]: λ1≤λ*… 相似文献
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Ning Zhao 《计算数学(英文版)》2001,(4)
1. IntroductionLet us consider the Cauchy problems for nonlinear hroerbolic scalar cO~ion laws:where the function f(u) E C'(R) and the hatal data ho E BV(R). As is well lmown, thisProblem in general does not ~ smooth solution, so that weak solution in the sense ofdistributions must be considered. Moreover, an elitropy condition must be added in order toensure the ~s of the weak solutions.The research of numerical methods for solving the equation (1.1) has been developed rapidlyin this deca… 相似文献
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The hierarchical reconstruction (HR) [Liu, Shu, Tadmor and Zhang, SINUM '07] has been successfully applied to prevent oscillations in solutions computed by finite volume, Runge-Kutta discontinuous Galerkin, spectral volume schemes for solving hyperbolic conservation laws. In this paper, we demonstrate that HR can also be combined with spectral/hp element method for solving hyperbolic conservation laws. An orthogonal spectral basis written in terms of Jacobi polynomials is applied. High computational efficiency is obtained due to such matrix-free algorithm. The formulation is conservative, and essential nomoscillation is enforced by the HR limiter. We show that HR preserves the order of accuracy of the spectral/hp element method for smooth solution problems and generate essentially non-oscillatory solutions profiles for capturing discontinuous solutions without local characteristic decomposition. In addition, we introduce a postprocessing technique to improve HR for limiting high degree numerical solutions. 相似文献
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This article is concerned with the pointwise error estimates for vanishing vis- cosity approximations to scalar convex conservation laws with boundary.By the weighted error function and a bootstrap extrapolation technique introduced by Tadmor-Tang,an optimal pointwise convergence rate is derived for the vanishing viscosity approximations to the initial-boundary value problem for scalar convex conservation laws,whose weak entropy solution is piecewise C 2 -smooth with interaction of elementary waves and the ... 相似文献
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李大明 《数学年刊A辑(中文版)》2003,(3)
本文讨论在无结构网格下用有限体积方法离散二维带非线性源项的单个守恒律,在测度值解与Diperna唯一性结果的框架下,证明了估计解在L_(loc)~l(R~2×(0,T))意义下收敛到单个守恒律的熵解。 相似文献
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王靖华 《数学物理学报(B辑英文版)》2009,29(3):613-628
We prove that for a given strictly increasing initial datum in Ck, the solution of the initial value problem is piecewise Ck smooth except for flux functions of nonconvex conservation laws in a certain subset of C^k+1 of first category, defined in the range of the initial datum. 相似文献