论文标题

线性稳定性分析通过模拟退火和加速放松

Linear stability analysis via simulated annealing and accelerated relaxation

论文作者

Furukawa, M., Morrison, P. J.

论文摘要

模拟退火(SA)是一种找到哈密顿系统平衡的放松方法。用SA求解了一组进化方程,该方程是从原始的哈密顿系统衍生而来的,因此系统的能量单调变化,同时保留了casimir不变性固有的固有的哈密顿系统。 SA达到的能量极值是平衡。由于SA搜索能量极值,因此当从将扰动添加到平衡的状态下,也可以用于稳定性分析。解释了稳定性分析的过程,并显示了一些示例。由于时间演化在计算上是耗时的,因此SA实际上有用的有效放松是必要的。通过在双括号中使用的对称内核中引入时间依赖性来开发加速方法,这是此处描述的SA公式的一部分。提出了低β降低磁通水力动力学(MHD)的明确配方。由于低β降低的MHD的SA具有两个放松的对流场,因此重要的是要平衡这些对流场的数量级。

Simulated annealing (SA) is a kind of relaxation method for finding equilibria of Hamiltonian systems. A set of evolution equations is solved with SA, which is derived from the original Hamiltonian system so that the energy of the system changes monotonically while preserving Casimir invariants inherent to noncanonical Hamiltonian systems. The energy extremum reached by SA is an equilibrium. Since SA searches for an energy extremum, it can also be used for stability analysis when initiated from a state where a perturbation is added to an equilibrium. The procedure of the stability analysis is explained, and some examples are shown. Because the time evolution is computationally time consuming, efficient relaxation is necessary for SA to be practically useful. An acceleration method is developed by introducing time dependence in the symmetric kernel used in the double bracket, which is part of the SA formulation described here. An explicit formulation for low-beta reduced magnetohydrodynamics (MHD) in cylindrical geometry is presented. Since SA for low-beta reduced MHD has two advection fields that relax, it is important to balance the orders of magnitude of these advection fields.

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