Flow-driven spectral chaos (FSC) method for simulating long-time dynamics of arbitrary-order non-linear stochastic dynamical systems

TL;DR

The paper introduces the flow-driven spectral chaos (FSC) method, a novel approach that efficiently and accurately simulates long-time dynamics of high-dimensional non-linear stochastic systems, overcoming the curse of dimensionality.

Contribution

The FSC method uses enriched stochastic flow maps to track the evolution of random function spaces, providing a more efficient and accurate alternative to traditional polynomial chaos methods.

Findings

FSC outperforms existing methods in efficiency and accuracy.

It effectively handles long-time stochastic dynamics.

Demonstrated success on high-dimensional problems with Monte Carlo integration.

Abstract

Uncertainty quantification techniques such as the time-dependent generalized polynomial chaos (TD-gPC) use an adaptive orthogonal basis to better represent the stochastic part of the solution space (aka random function space) in time. However, because the random function space is constructed using tensor products, TD-gPC-based methods are known to suffer from the curse of dimensionality. In this paper, we introduce a new numerical method called the 'flow-driven spectral chaos' (FSC) which overcomes this curse of dimensionality at the random-function-space level. The proposed method is not only computationally more efficient than existing TD-gPC-based methods but is also far more accurate. The FSC method uses the concept of 'enriched stochastic flow maps' to track the evolution of a finite-dimensional random function space efficiently in time. To transfer the probability information from one random function space to another, two approaches are developed and studied herein. In the first approach, the probability information is transferred in the mean-square sense, whereas in the second approach the transfer is done exactly using a new theorem that was developed for this purpose. The FSC method can quantify uncertainties with high fidelity, especially for the long-time response of stochastic dynamical systems governed by ODEs of arbitrary order. Six representative numerical examples, including a nonlinear problem (the Van-der-Pol oscillator), are presented to demonstrate the performance of the FSC method and corroborate the claims of its superior numerical properties. Finally, a parametric, high-dimensional stochastic problem is used to demonstrate that when the FSC method is used in conjunction with Monte Carlo integration, the curse of dimensionality can be overcome altogether.