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arXiv 2008.07427math.NAcs.NA
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哈密顿系统的动力学缩减基方法

Dynamical reduced basis methods for Hamiltonian systems

Cecilia Pagliantini

摘要:

我们考虑模型降阶参数化哈密顿系统描述非耗散现象,如波型和输运主导的问题。这种模型的减少的基础方法的发展受到两个主要因素的挑战:丰富的几何结构编码的物理和稳定性的动态和其本地低秩性质。为了解决这些问题,我们提出了一个非线性结构保持模型减少相空间的时间演变。在动力学低秩近似的精神下,约化动力学通过在每个约化状态下将Hamilton向量场辛投影到近似流形的切空间上来获得。先验误差估计建立在简化流形上的全模型解的投影误差方面。对于时间离散化的减少动态,我们采用分裂技术。简化的基础满足一个发展方程上的流形的辛和正交矩形矩阵具有一个维度等于的大小的完整的模型。我们重铸的问题上的切空间的矩阵流形和发展的内在时间积分的基础上李群技术与显式龙格库塔(RK)计划。所得到的方法收敛与RK积分器的顺序和他们的计算复杂性仅线性依赖于完整模型的尺寸,提供的减少流速的评估具有可比的成本。

英文摘要:

We consider model order reduction of parameterized Hamiltonian systems describing nondissipative phenomena, like wave-type and transport dominated problems. The development of reduced basis methods for such models is challenged by two main factors: the rich geometric structure encoding the physical and stability properties of the dynamics and its local low-rank nature. To address these aspects, we propose a nonlinear structure-preserving model reduction where the reduced phase space evolves in time. In the spirit of dynamical low-rank approximation, the reduced dynamics is obtained by a symplectic projection of the Hamiltonian vector field onto the tangent space of the approximation manifold at each reduced state. A priori error estimates are established in terms of the projection error of the full model solution onto the reduced manifold. For the temporal discretization of the reduced dynamics we employ splitting techniques. The reduced basis satisfies an evolution equation on the manifold of symplectic and orthogonal rectangular matrices having one dimension equal to the size of the full model. We recast the problem on the tangent space of the matrix manifold and develop intrinsic temporal integrators based on Lie group techniques together with explicit Runge-Kutta (RK) schemes. The resulting methods are shown to converge with the order of the RK integrator and their computational complexity depends only linearly on the dimension of the full model, provided the evaluation of the reduced flow velocity has a comparable cost.

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