共查询到19条相似文献,搜索用时 854 毫秒
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在已有MLSPH(Moving Least Squares Particle Hydrodynamics)方法研究的基础上,进一步研究MLSPH方法在流体力学计算方面的应用,探索它模拟计算内爆的适用性。 相似文献
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讨论一维和二维非线性Schr(o)dinger (NLS)方程的数值求解.基于扩散广义黎曼问题的数值流量,构造一种直接间断Galerkin方法(DDG)求解非线性Schr(o)dinger方程.证明该方法L2稳定性,并说明DDG格式是一种守恒的数值格式.对一维NLS方程的计算表明,DDG格式能够模拟各种孤立子形态,而且可以保持长时间的高精度.二维NLS方程的数值结果显示该方法的高精度和捕捉大梯度的能力. 相似文献
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设计了一维无限深势阱中粒子概率密度演示仪,利用粒子的态函数的驻波图像来演示粒子的概率密度,使学生能直观地观察一维无限深势阱内粒子的概率密度分布规律. 相似文献
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采用改进的光滑粒子动力学(SPH)方法对液滴冲击固壁面问题进行了数值模拟. 为了提高传统SPH方法的计算精度和数值稳定性, 在传统的SPH方法的基础上对粒子方法中的密度和核梯度进行了修正, 采用了考虑黎曼解法的SPH流体控制方程, 构造了一种新型的粒子间相互作用力(IIF)模型来模拟表面张力的影响. 应用改进的SPH方法对液滴冲击固壁面问题进行了数值模拟. 计算结果表明:新型的IIF 模型能够较好地模拟表面张力的影响, 改进的SPH方法能够精细地描述液滴与固壁面相互作用过程中液滴的内部压力场演变和自由面形态变化, 液滴的铺展因子随初始韦伯数的增大而增大, 数值模拟结果与实验得到的结果基本一致.
关键词:
液滴
固壁面
光滑粒子动力学
表面张力 相似文献
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对二维空气动力学方程组的分三片Riemann问题中只含接触间断的情况进行分类分析,并利用文献[1]所提出的正规三角形网格上Taylor-FVMMmB差分格式对该问题进行数值计算。从数值结果来看,分三片Riemann问题是二维空气动力学方程组Riemann问题中的最简单的初值分布,所形成解的结构也是最基本的。 相似文献
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《Physics letters. A》1998,245(5):373-381
The general solution of a 7D analogue of the 3D Euler top equation is shown to be given by an integration over a Riemann surface with genus 9. The 7D model is derived from the 8D Spin(7) invariant self-dual Yang-Mills equation depending only upon one variable and is regarded as a model describing self-dual membrane instantons. Several integrable reductions of the 7D top to lower target space dimensions are discussed and one of them gives 6, 5, 4D descendants and the 3D Euler top associated with Riemann surfaces with genus 6, 5, 2 and 1, respectively. 相似文献
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采用光滑粒子流体动力学(SPH)方法模拟大变形问题具有明显的优点,但传统的SPH方法在模拟冲击波与接触界面的作用时,往往会出现压力的反常跳动。采用黎曼解描述粒子间相互作用的接触算法对传统SPH方法进行修正,计算了激波管和飞片碰撞(包含接触界面)问题中波的传播,并将计算结果与解析解作比较。结果表明,与传统的光滑粒子法相比,该改进的光滑粒子法无需引入人工粘性项和人工热流项,程序结构简洁,且能较好地处理接触界面问题,从而能有效提高计算精度。 相似文献
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Dinshaw S. Balsara 《Journal of computational physics》2012,231(22):7476-7503
In this paper we present a genuinely two-dimensional HLLC Riemann solver. On logically rectangular meshes, it accepts four input states that come together at an edge and outputs the multi-dimensionally upwinded fluxes in both directions. This work builds on, and improves, our prior work on two-dimensional HLL Riemann solvers. The HLL Riemann solver presented here achieves its stabilization by introducing a constant state in the region of strong interaction, where four one-dimensional Riemann problems interact vigorously with one another. A robust version of the HLL Riemann solver is presented here along with a strategy for introducing sub-structure in the strongly-interacting state. Introducing sub-structure turns the two-dimensional HLL Riemann solver into a two-dimensional HLLC Riemann solver. The sub-structure that we introduce represents a contact discontinuity which can be oriented in any direction relative to the mesh.Media player
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In this paper, the solution of the Riemann Problem for the one-dimensional, free-surface Shallow Water Equations over a bed step is analyzed both from a theoretical and a numerical point of view. Particular attention has been paid to the wave that is generated at the location of the bed discontinuity. Starting from the classical Shallow Water Equations, considering the bed level as an additional variable, and adding to the system an equation imposing its time invariance, we show that this wave is a contact wave, across which one of the Riemann invariants, namely the energy, is not constant. This is due to the fact that the relevant problem is nonconservative. We demonstrate that, in this type of system, Riemann Invariants do not generally hold in contact waves. Furthermore, we show that in this case the equations that link the flow variables across the contact wave are the Generalized Rankine–Hugoniot relations and we obtain these for the specific problem. From the numerical point of view, we present an accurate and efficient solver for the step Riemann Problem to be used in a finite-volume Godunov-type framework. Through a two-step predictor–corrector procedure, the solver is able to provide solutions with any desired accuracy. The predictor step uses a well-balanced Generalized Roe solver while the corrector step solves the exact nonlinear system of equations that consitutes the problem by means of an iterative procedure that starts from the predictor solution. In order to show the effectiveness and the accuracy of the proposed approach, we consider several step Riemann Problems and compare the exact solutions with the numerical results obtained by using a standard Roe approach far from the step and the novel two-step algorithm for the fluxes over the step, achieving good results. 相似文献
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We investigate the nonlinear holomorphic supersymmetry for quantum-mechanical systems on Riemann surfaces subjected to an external magnetic field. The realization is shown to be possible only for Riemann surfaces with constant curvature metrics. The cases of the sphere and Lobachevski plane are elaborated in detail. The partial algebraization of the spectrum of the corresponding Hamiltonians is proved by the reduction to one-dimensional quasi-exactly solvable
families. It is found that these families possess the “duality” transformations, which form a discrete group of symmetries of the corresponding 1D potentials and partially relate the spectra of different 2D systems. The algebraic structure of the systems on the sphere and hyperbolic plane is explored in the context of the Onsager algebra associated with the nonlinear holomorphic supersymmetry. Inspired by this analysis, a general algebraic method for obtaining the covariant form of integrals of motion of the quantum systems in external fields is proposed. 相似文献
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《Nuclear Physics B》1996,477(3):855-877
The interpretation of exact results on the low-energy limit of 4D N = 2 supersymmetric Yang-Mills theory in the language of 1D integrable system of particles is discussed. The Riemann surfaces of the Seiberg-Witten theory are explicitly described as spectral curves of Lax operators. The case of the elliptic Calogero system, associated with the flow between N = 4 and N = 2 supersymmetric in 4D, is considered in some detail. Equations for the corresponding Riemann surfaces are written down rather explicitly for all the SU(n) groups. 相似文献
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JIN Cui-Lian 《理论物理通讯》2008,50(5):1027-1032
In this paper, we investigate a class of mixed initial-boundary value problems for a kind of n×n quasilinear hyperbolic systems of conservation laws on the quarter plan. We show that the
structure of the piecewise
C1 solution u=u(t,x) of the problem, which can be regarded as a perturbation of the corresponding Riemann problem, is globally similar to that of the solution u=U(x/t) of the corresponding Riemann problem. The piecewise C1
solution u=u(t,x) to this kind of problems is globally structure-stable if and only if it contains only non-degenerate shocks and contact discontinuities, but no rarefaction waves and other weak discontinuities. 相似文献
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T. Gulden M. Janas P. Koroteev A. Kamenev 《Journal of Experimental and Theoretical Physics》2013,117(3):517-537
Statistical mechanics of a 1D multivalent Coulomb gas can be mapped onto non-Hermitian quantum mechanics. We use this example to develop the instanton calculus on Riemann surfaces. Borrowing from the formalism developed in the context of the Seiberg-Witten duality, we treat momentum and coordinate as complex variables. Constant-energy manifolds are given by Riemann surfaces of genus g ≥ 1. The actions along principal cycles on these surfaces obey the ordinary differential equation in the moduli space of the Riemann surface known as the Picard-Fuchs equation. We derive and solve the Picard-Fuchs equations for Coulomb gases of various charge content. Analysis of monodromies of these solutions around their singular points yields semiclassical spectra as well as instanton effects such as the Bloch bandwidth. Both are shown to be in perfect agreement with numerical simulations. 相似文献