搜索结果: 1-15 共查到“理学 Helmholtz”相关记录38条 . 查询时间(0.238 秒)
Kelvin-Helmholtz（KH）不稳定性是一种由边界剪切流引起的不稳定性，在具有全球性磁场的行星（如地球和水星）以及没有全球磁场的行星（如金星和火星）的等离子环境中广泛存在。KH不稳定性发展到非线性阶段时会产生涡旋，其运动可以扭曲磁场并引起磁场拓扑的改变，导致等离子云的产生并从行星电离层脱离，造成重离子的丢失。KH不稳定性对边界层质量、动量和能量传输都有显著影响，因此在行星的等离子环境研究...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Dispersion Analysis of CIP–FEM for Helmholtz Equation
亥姆霍兹方程 CIP-FEM 色散分析
2023/4/24
When solving the Helmholtz equation numerically, the accuracy of numerical solution deteriorates as the wave number k increases, known as `pollution effect' which is directly related to the phase diff...
Maxwell特征值问题的两水平预处理Helmholtz-Jacobi-Davidson方法
Maxwell特征值 水平预处理 Helmholtz-Jacobi-Davidson方法
2023/1/5
In this paper, based on a domain decomposition (DD) method, we shall propose an efficient two-level preconditioned Helmholtz-Jacobi-Davidson (PHJD) method for solving the algebraic eigenvalue problem ...
中国科学院国家空间科学中心科研人员与合作者首次在卫星观测中发现Kelvin-Helmholtz涡旋中嵌套Rayleigh-Taylor不稳定性的证据（图）
卫星观测 Kelvin-Helmholtz涡旋 Rayleigh-Taylor不稳定性
2023/2/16
太阳风向磁层的传输是磁层物理研究的一个基本问题。太阳风是太阳大气向外膨胀而形成的超声速带电粒子流，当太阳风遇到地球内禀磁场的阻挡时，会形成一个被称为地球磁层的空腔，空腔的外边界称为磁层顶。由于磁冻结效应（就像串绳约束着它所贯穿的许多珠子），磁层顶把来自地球的热等离子体与来自太阳风的冷等离子体隔开，使太阳风在这个空腔外围绕过，从而像盾牌一样为空腔里的地球提供了免于太阳风直接轰击的天然屏护，这是地球上...
中国科学院国家空间中心科研人员与合作者首次在卫星观测中发现Kelvin-Helmholtz涡旋中嵌套Rayleigh-Taylor不稳定性的证据（图）
卫星观测 磁层物理 热等离子体
2023/8/22
太阳风向磁层的传输是研究的一个基本问题。太阳风是太阳大气向外膨胀而形成的超声速带电粒子流，当太阳风遇到地球内禀磁场的阻挡时，会形成一个被称为地球磁层的空腔，空腔的外边界称为磁层顶。由于磁冻结效应（就像串绳约束着它所贯穿的许多珠子），磁层顶把来自地球的热等离子体与来自太阳风的冷等离子体隔开，使太阳风在这个空腔外围绕过，从而像盾牌一样为空腔里的地球提供了免于太阳风直接轰击的天然屏护，这是地球上存在宜居...
大波数Helmholtz和Maxwell方程拟周期格林函数的快速算法
积分方程方法 计算拟周期 格林函数
2021/8/25
积分方程方法是求解散射问题的常用数值方法，而积分方程法需要格林函数的大量数值计算。周期结构声波和电磁波散射问题（物理上又称为衍射光栅）中的格林函数是拟周期的而且以级数形式给出，因此，它的数值计算非常困难。由于周期结构散射问题在绕射光学、光学元器件的设计与制作等许多领域具有极其重要的应用，因此，人们提出了很多计算拟周期格林函数的快速算法（Linton, SIAM Rev. 52 (2010), 63...
Fast directional algorithms for the Helmholtz kernel
N-body problems Scattering problems Helmholtz equation Oscillatory kernels Fast multipole methods Separated representations Random sampling Operator compression Multidirectional computation Multiscale methods
2015/7/14
This paper presents a new directional multilevel algorithm for solving N-body or N-point problems with highly oscillatory kernels. We address the problem by first proving that the interaction between ...
Sweeping Preconditioner for the Helmholtz Equation:Hierarchical Matrix Representation
Sweeping Preconditioner Helmholtz Equation Hierarchical Matrix Representation
2015/7/14
The paper introduces the sweeping preconditioner, which is highly efficient for iterative solutions of the variable-coefficient Helmholtz equation including veryhigh-frequency problems. The first cent...
SWEEPING PRECONDITIONER FOR THE HELMHOLTZ EQUATION: MOVING PERFECTLY MATCHED LAYERS
Helmholtz equation perfectly matched layers high frequency waves preconditioners LDLt factorization Green’s function multifrontal methods optimal ordering
2015/7/14
This paper introduces a new sweeping preconditioner for the iterative solution of the variable coefficient Helmholtz equation in two and three dimensions. The algorithms follow the general structure o...
A PARALLEL SWEEPING PRECONDITIONER FOR HETEROGENEOUS 3D HELMHOLTZ EQUATIONS
Helmholtz time-harmonic sweeping preconditioner parallel
2015/7/14
A parallelization of a sweeping preconditioner for 3D Helmholtz equations without internal resonance is introduced and benchmarked for several challenging velocity models. The setup and application co...
Additive Sweeping Preconditioner for the Helmholtz Equation
Helmholtz equation perfectly matched layers preconditioners high frequency waves
2015/7/14
We introduce a new additive sweeping preconditioner for the Helmholtz equation based on the perfect matched layer (PML). This method divides the domain of interest into thin layers and proposes a new ...
Recursive Sweeping Preconditioner for the 3D Helmholtz Equation
Helmholtz equation perfectly matched layers preconditioners high frequency waves
2015/7/14
This paper introduces the recursive sweeping preconditioner for the numerical solution of the Helmholtz equation in 3D. This is based on the earlier work of the sweeping preconditioner with the moving...
Kelvin-Helmholtz (KH) instability, characterized by the distinctive
finite-amplitude billows it generates, is an important mechanism in the development
of turbulence in the stratified interior of ...
近日，中国科学院空间科学与应用研究中心空间天气国家重点实验室科研人员燕广庆等及时追踪了THEMIS卫星的观测资料并进行了细致分析，获取了行星际磁场南向期间Kelvin-Helmholtz涡旋的难得观测证据，进一步通过卫星观测事实证明了在行星际磁场南向期间也可以发生具有规则周期性的Kelvin-Helmholtz涡旋，客观地打破了Kelvin-Helmholtz涡旋只能在行星际磁场北向条件下发生的传...
正演是电磁法勘探野外工作参数选取、室内资料处理与解释的基础，精确、稳定、高效的三维正演算法尤为重要.本文采取先求解拉普拉斯域电场、再由Gaver-Stehfest算法获得时间域磁场的思路，基于电场异常场Helmholtz方程实现了交错网格有限差分法和有限体积法对回线源瞬变电磁法的三维正演.通过对比低阻块状体的积分方程法、时域有限差分法、矢量有限单元法和SLDM法的数值解，验证了交错网格有限差分法和...