共查询到20条相似文献,搜索用时 78 毫秒
1.
数值模拟混溶驱动问题的迎风格式及理论分析 总被引:7,自引:2,他引:7
梁栋 《高校应用数学学报(A辑)》1994,(2):118-127
本文提出数据模拟混溶驱动问题的一类广义迎风格式,严格证明了其满足离散极值原理和离散质量守恒原理,并获得收敛性定理,对模型问题的试算,得到令人满意的数值结果。 相似文献
2.
崔明荣 《高校应用数学学报(A辑)》1999,14(3):333-340
考虑了三维油藏数值模拟中的动边值问题,对压力方程,给出中心差分格式;对饱和度方程给出隐式迎风差分格式及修正的迎风差分格式,并证明了格式的收敛性。数值算例与理论结果是一致的。 相似文献
3.
4.
以四阶CWENO重构为基础,通过将对流项采用低耗散中心迎风格式离散,扩散项采用四阶中心差分格式离散,对得到的半离散格式采用四阶龙格库塔方法在时间方向上推进,得到一种求解对流扩散方程的高阶有限差分格式.数值结果验证了该格式的四阶精度和基本无振荡特性. 相似文献
5.
6.
对多层非线性渗流方程耦合系统三维动边值问题, 提出适合并行计算的一类二阶迎风分数步差分格式, 利用区域变换、变分形式、能量方法、隐显格式的相互结合、差分算子乘积交换性、高阶差分算子的分解、先验估计的理论和技巧, 得到收敛性的最佳阶l2 误差估计. 该方法已成功地应用到多层油资源运移聚集的资源评估生产实际中, 得到了很好的数值模拟结果. 相似文献
7.
本文给出了一种求解不可压缩流动问题的高精度差分格式,即迎风紧致格式.出发方程采用二维非定常原始变量Naiver-Stokes方程组.在差分方程中,对流项采用三阶精度的迎风紧致差分,其余空间导数项采用四阶紧致差分.本文利用该差分格式在等距网格上数值模拟了驱动方腔流动中的分离涡运动.在257×257的细网格上,Re数最高计算到10000.Re≤5000时的计算结果与前人结果符合得很好.当Re≥7500时发现流动不存在定常层流解而为非定常周期性解,并首次给出了非定常解的结果。 相似文献
8.
9.
将求解双曲型守恒律方程的低耗散中心迎风格式和5阶WENO-ZQ格式相结合,推广应用于求解二相LWR交通流模型方程.并在时间方向上推进采用具有强稳定性的4阶Rung-Kutta方法.最后结合Riemann问题及现实生活所遇到的交通流现象进行设计和分析.通过数值算例证明该格式具较强的稳定性和较高的精度,得到了令人满意的结果. 相似文献
10.
设~$G=KP$, 其中~$K$是有限生成的~$p’$-\!自由的幂零群, $P$ 是有限秩的幂零~$p$-\!群, 并且~$[K,P]=1$, 即~$G$ 是~$K$ 和~$P$ 的中心积, $\alpha$ 和~$\beta$是~$G$ 的两个~$p$-\!自同构, 记~$I:=\langle\left(\alpha\beta(g)\right)\cdot\left(\beta\alpha(g)\right)^{-1} \,|\, g\in G \rangle$, 则 {\rm(i)} 当~$I=Z_{p^n}\oplus Z_{p^{\infty}}$ 时, $\alpha$ 和~$\beta$生成一个可解的剩余有限~$p$-\!群, 它是有限生成的无挠幂零群被有限~$p$-\! 群的扩张; 在下列3种情形下, $\alpha$ 和~$\beta$生成一个可解的剩余有限~$p$-\!群, 其幂零长度不超过~$3$. {\rm(ii)} 当~$I=Z\oplus Z_{p^{\infty}}$ 时; {\rm(iii)} 当$I$ 有正规列~$1< J< I$, 其商因子分别为无限循环群和有限循环群时; {\rm(iv)} 当~$I$ 有正规列~$1< L< J< I$, 其3个商因子分别为无限循环群、有限循环群和拟循环~$p$-\!群时. 特别地, 当上述群~$K$ 是一个~$FC$-群时, $\alpha$ 和~$\beta$ 生成的群是有限生成的无挠幂零群被有限~$p$-\!群的扩张. 相似文献
11.
Bryson Steve; Kurganov Alexander; Levy Doron; Petrova Guergana 《IMA Journal of Numerical Analysis》2005,25(1):113-138
We introduce a new family of Godunov-type semi-discrete centralschemes for multidimensional HamiltonJacobi equations.These schemes are a less dissipative generalization of the central-upwindschemes that have been recently proposed in Kurganov, Noelleand Petrova (2001, SIAM J. Sci. Comput., 23, pp. 707740).We provide the details of the new family of methods in one,two, and three space dimensions, and then verify their expectedlow-dissipative property in a variety of examples. 相似文献
12.
In this paper, we prove the existence of global smooth solution for the Cauchy problem of nonlinearly damped p-system with large initial data. The analysis is based on several key a prioriestirmates. which are obtained by the tnaxirnum principle. Our results extend the corresponding results in [l0,11]. 相似文献
13.
Semidiscrete central-upwind scheme for conservation laws with a discontinuous flux function in space
In this paper, a modified semidiscrete central-upwind scheme is derived for the scalar conservation laws with a discontinuous flux function in space. The new scheme is based on dealing with the phase transition at the stationary discontinuity, where the unknown variable function is not continuous, but the flux function is continuous. The main advantages of the new scheme are the same as them of the original semidiscrete central-upwind scheme. Numerical results are displayed to illustrate the efficiency of the methods. 相似文献
14.
Laurent Gosse. 《Mathematics of Computation》2002,71(238):553-582
This paper investigates the behavior of numerical schemes for nonlinear conservation laws with source terms. We concentrate on two significant examples: relaxation approximations and genuinely nonhomogeneous scalar laws. The main tool in our analysis is the extensive use of weak limits and nonconservative products which allow us to describe accurately the operations achieved in practice when using Riemann-based numerical schemes. Some illustrative and relevant computational results are provided.
15.
C. Berthon C. Chalons R. Turpault 《Numerical Methods for Partial Differential Equations》2013,29(4):1149-1172
We devise a new class of asymptotic‐preserving Godunov‐type numerical schemes for hyperbolic systems with stiff and nonstiff relaxation source terms governed by a relaxation time ε. As an alternative to classical operator‐splitting techniques, the objectives of these schemes are twofold: first, to give accurate numerical solutions for large, small, and in‐between values of ε and second, to make optional the choice of the numerical scheme in the asymptotic regime ε tends to zero. The latter property may be of particular interest to make easier and more efficient the coupling at a fixed spatial interface of two models involving very different values of ε. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2013 相似文献
16.
Mircea Mustata 《Journal of the American Mathematical Society》2002,15(3):599-615
Let be a smooth variety and a closed subscheme. We use motivic integration on the space of arcs of to characterize the fact that is log canonical or log terminal using the dimension of the jet schemes of . This gives a formula for the log canonical threshold of , which we use to prove a result of Demailly and Kollár on the semicontinuity of log canonical thresholds.
17.
18.
Jaume Martí-Farré 《Discrete Applied Mathematics》2006,154(3):552-563
The characterization of ideal access structures and the search for bounds on the optimal information rate are two important problems in secret sharing. These problems are studied in this paper for access structures with intersection number equal to one, that is, structures such that there is at most one participant in the intersection of any two different minimal qualified subsets. The main result in this work is the complete characterization of the ideal access structures with intersection number equal to one. In addition, bounds on the optimal information rate are provided for the non-ideal case. 相似文献
19.
Aleksandrs Slivkins 《Discrete Mathematics》2009,309(13):4384-4398
Interleaving is used for error-correcting on a bursty noisy channel. Given a graph G describing the topology of the channel, we label the vertices of G so that each label-set is sufficiently sparse. The interleaving scheme corrects for any error burst of size at most t; it is a labeling where the distance between any two vertices in the same label-set is at least t.We consider interleaving schemes on infinite circulant graphs with two offsets 1 and d. In such a graph the vertices are integers; edge ij exists if and only if |i−j|∈{1,d}. Our goal is to minimize the number of labels used.Our constructions are covers of the graph by the minimal number of translates of some label-set S. We focus on minimizing the index of S, which is the inverse of its density rounded up. We establish lower bounds and prove that our constructions are optimal or almost optimal, both for the index of S and for the number of labels. 相似文献
20.
In this study an explicit central difference approximation of the generalized leap-frog type is applied to the one- and two-dimensional advection equations. The stability of the considered numerical schemes is investigated and the scheme with the largest stable time step is found. For the linear and nonlinear advection equations numerical experiments with different schemes from the considered class are performed in order to evaluate the practical stability of the designed schemes. 相似文献