Carassale, L. (2012). Interpretation of wind-induced pressure fields by
Independent Component Analysis,
Probabilistic
Engineering Mechanics, 28, 66-74.
Abstract
Aerodynamic
pressure measurements are usually interpreted through statistical tools
involving modal representations. The most popular approach is based on the
Principal Component Analysis (PCA), which provides the theoretical basis for
the well-known concept of coherent structure. In order to overcome some theoretical
and practical limitations, alternative approaches can be formulated adapting
techniques developed in the feature-recognition field. In this sense, the
Independent Component Analysis (ICA) can be conceived as an evolution of PCA in
which high-order statistics are used to identify a non-orthogonal modal
representation; ICA has been used to solve the Blind Source Separation (BSS)
problem as well as to extract features from random data. Both PCA and ICA show
severe limitations when applied to represent (and interpret) propagating
phenomena such as the pressure field generated by a vortex advected by the mean
flow. To overcome these problems, an explicit description of the time evolution
is introduced in the modal representation through two techniques, Dynamic-PCA
and Dynamic-ICA; besides, the novel concept of dynamic coherent structure is
presented and used as an interpretative tool. The application of the
above-mentioned methods is demonstrated referring to the aerodynamic pressure
field measured on a bluff body immersed in a turbulent boundary layer.
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