论文标题

微麦克罗分解的减少基础方法,用于时间依赖性辐射转移方程

A micro-macro decomposed reduced basis method for the time-dependent radiative transfer equation

论文作者

Peng, Zhichao, Chen, Yanlai, Cheng, Yingda, Li, Fengyan

论文摘要

众所周知,动力学传输方程很难模拟,因为它们具有复杂的多尺度行为,并且需要数字解决高维概率密度函数。过去的文献专注于通过分析方法构建减少订单模型(ROM)。近年来,使用数据驱动或计算工具提供了更适用性和灵活性,人们对开发ROM的兴趣激增。本文是朝着该方向发展的工作。 由我们以前在[30]中为固定辐射传递方程设计ROM的工作所激发的,它利用了由角变量引起的溶液歧管的低级别结构,我们在这里进一步将方法论进一步推进了时间依赖的模型。特别是,我们采用了著名的减少基础方法(RBM)方法,并提出了一种新型的微麦克罗分解减少基础方法(MMD-RBM)。 MMD-RBM是通过以贪婪的方式利用微小和宏分解歧管相对于角变量和时间变量来构建的。我们减少的阶替代物包括:减少订单子空间的碱基和角度空间中的正交规则降低。提出的MMD-RBM具有几个结构性保护组件:1)构建降低的订单子空间的均衡策略,更好地利用了分解系统的结构,以及2)一个配方,用于保持正交权重的积极性,从而维持基础底层减少的溶剂固定剂的稳定性。所得的ROM可用于在训练集之外的角度方向和角磁力的任意顺序矩形方向上快速在线求解。

Kinetic transport equations are notoriously difficult to simulate because of their complex multiscale behaviors and the need to numerically resolve a high dimensional probability density function. Past literature has focused on building reduced order models (ROM) by analytical methods. In recent years, there is a surge of interest in developing ROM using data-driven or computational tools that offer more applicability and flexibility. This paper is a work towards that direction. Motivated by our previous work of designing ROM for the stationary radiative transfer equation in [30] by leveraging the low-rank structure of the solution manifold induced by the angular variable, we here further advance the methodology to the time-dependent model. Particularly, we take the celebrated reduced basis method (RBM) approach and propose a novel micro-macro decomposed reduced basis method (MMD-RBM). The MMD-RBM is constructed by exploiting, in a greedy fashion, the low-rank structures of both the micro- and macro-solution manifolds with respect to the angular and temporal variables. Our reduced order surrogate consists of: reduced bases for reduced order subspaces and a reduced quadrature rule in the angular space. The proposed MMD-RBM features several structure-preserving components: 1) an equilibrium-respecting strategy to construct reduced order subspaces which better utilize the structure of the decomposed system, and 2) a recipe for preserving positivity of the quadrature weights thus to maintain the stability of the underlying reduced solver. The resulting ROM can be used to achieve a fast online solve for the angular flux in angular directions outside the training set and for arbitrary order moment of the angular flux.

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