We consider the frequency domain form of proper orthogonal decomposition (POD), called
spectral proper orthogonal decomposition (SPOD). Spectral POD is derived from a space …

Organized structures in turbulent jets can be modeled as wavepackets. These are
characterized by spatial amplification and decay, both of which are related to stability …

This paper discusses the spectral proper orthogonal decomposition and its use in identifying
modes, or structures, in flow data. A specific algorithm based on estimating the cross …

The Koopman theory, a concept to globally model nonlinear signals by a linear Hamiltonian,
has been at the frontier of fluid mechanics research for the last decade. Wind engineering …

Four different applications of spectral proper orthogonal decomposition (SPOD) are
demonstrated on large-eddy simulation data of a turbulent jet. These are: low-rank …

Resolvent analysis identifies the most responsive forcings and most receptive states of a
dynamical system, in an input–output sense, based on its governing equations. Interest in …

The interaction between various wave-like structures in screeching jets is considered via
both experimental measurements and linear stability theory. Velocity snapshots of …

Response modes computed via linear resolvent analysis of a turbulent mean-flow field have
been shown to qualitatively capture characteristics of the observed turbulent coherent …

Three amplification mechanisms present in turbulent jets, namely lift-up, Kelvin–Helmholtz
and Orr, are characterized via global resolvent analysis and spectral proper orthogonal …

To identify the spatiotemporal coherent structure of compressor tip leakage flow, spectral
proper orthogonal decomposition (SPOD) is performed on the near-tip flow field and the …