Four different applications of spectral proper orthogonal decomposition (SPOD) are demonstrated on large-eddy simulation data of a turbulent jet. These are: low-rank reconstruction, denoising, frequency–time analysis and prewhitening. We demonstrate SPOD-based flow-field reconstruction using direct inversion of the SPOD algorithm (frequency-domain approach) and propose an alternative approach based on projection of the time series data onto the modes (time-domain approach). We further present a SPOD-based denoising strategy that is based on hard thresholding of the SPOD eigenvalues. The proposed strategy achieves significant noise reduction while facilitating drastic data compression.
Literature:
- Nekkanti, A. and O. T. Schmidt. “Frequency–time analysis, low-rank reconstruction and denoising of turbulent flows using spod.” Journal of fluid mechanics 926 (2021): A26.
[Bibtex]@Article{nekkantischmidt_2021_jfm, author = {Nekkanti, A. and Schmidt, O. T.}, journal = {Journal of Fluid Mechanics}, title = {Frequency–time analysis, low-rank reconstruction and denoising of turbulent flows using SPOD}, year = {2021}, pages = {A26}, volume = {926}, doi = {10.1017/jfm.2021.681}, file = {:NekkantiSchmidt_2021_JFM.pdf:PDF}, publisher = {Cambridge University Press}, }
Code:
Example 7 and routine tcoeffs.m in SPOD package on MATLAB Central File Exchange