Networked oscillator based modeling and control of unsteady wakes

Abstract

A networked oscillator based analysis is performed for periodic bluff body flows to examine and control the transfer of kinetic energy. Spatial modes extracted from the flow field with corresponding amplitudes form a set of oscillators describing unsteady fluctuations. These oscillators are connected through a network that captures the energy exchanges amongst them. To extract the network of interactions among oscillators, amplitude and phase perturbations are impulsively introduced to the oscillators and the ensuing dynamics are analyzed. Using linear regression techniques, a networked oscillator model is constructed that reveals energy transfers and phase interactions among the modes. The model captures the nonlinear interactions amongst the modal oscillators through a linear approximation. A large collection of system responses are aggregated into a network model that captures interactions for general perturbations. The networked oscillator model describes the modal perturbation dynamics better than the empirical Galerkin reduced-order models. A model-based feedback controller is then designed to suppress modal amplitudes and the resulting wake unsteadiness leading to drag reduction. The strength of the proposed approach is demonstrated for a canonical example of two- dimensional unsteady flow over a circular cylinder. The present formulation enables the characterization of modal interactions to control fundamental energy transfers in unsteady vortical flows.

33 pages, 16 figures

References in corpus (7)

• Chaos as an Intermittently Forced Linear System
• Two-dimensional compressible viscous flow around a circular cylinder
• Network Structure of Two-Dimensional Decaying Isotropic Turbulence
• Collective Phase Sensitivity
• Network-theoretic approach to sparsified discrete vortex dynamics
• Structure-Preserving Galerkin POD Reduced-Order Modeling of Hamiltonian Systems
• Constrained Sparse Galerkin Regression

Cited by in corpus (18)

• Cluster-based feedback control of turbulent post-stall separated flows
• A review on turbulent and vortical flow analyses via complex networks
• Data-driven transient lift attenuation for extreme vortex gust-airfoil interactions
• Identifying vortical network connectors for turbulent flow modification
• Phase-based control of periodic fluid flows
• Phase-synchronization properties of laminar cylinder wake for periodic external forcings
• Modal Analysis of Fluid Flows: Applications and Outlook
• Mechanisms of a Convolutional Neural Network for Learning Three-dimensional Unsteady Wake Flow
• Phase-consistent dynamic mode decomposition from multiple overlapping spatial domains
• Randomized methods to characterize large-scale vortical flow network
• Modal Analysis of Fluid Flows: An Overview
• Network-theoretic modeling of fluid-structure interactions
• Revealing essential dynamics from high-dimensional fluid flow data and operators
• Network-based analysis of fluid flows: Progress and outlook
• Estimating regression errors without ground truth values
• Vortical interactions in turbulent thermoacoustic systems
• Hilbert Proper Orthogonal Decomposition: a tool for educing advective wavepackets from flow field data
• $l_1$-based sparsification of energy interactions in two-dimensional turbulent flows