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Materials Science and Engineering

Portland State University

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Orthogonal decompositions

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Articles 1 - 2 of 2

Full-Text Articles in Engineering

Anisotropic Character Of Low-Order Turbulent Flow Descriptions Through The Proper Orthogonal Decomposition, Nicholas Hamilton, Murat Tutkun, Raúl Bayoán Cal Jan 2017

Anisotropic Character Of Low-Order Turbulent Flow Descriptions Through The Proper Orthogonal Decomposition, Nicholas Hamilton, Murat Tutkun, Raúl Bayoán Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

Proper orthogonal decomposition (POD) is applied to distinct data sets in order to characterize the propagation of error arising from basis truncation in the description of turbulence. Experimental data from stereo particle image velocimetry measurements in a wind turbine array and direct numerical simulation data from a fully developed channel flow are used to illustrate dependence of the anisotropy tensor invariants as a function of POD modes used in low-order descriptions. In all cases, ensembles of snapshots illuminate a variety of anisotropic states of turbulence. In the near wake of a model wind turbine, the turbulence field reflects the periodic …


Focused-Based Multifractal Analysis Of The Wake In A Wind Turbine Array Utilizing Proper Orthogonal Decomposition, Naseem Ali, Hawwa Falih Kadum, Raúl Bayoán Cal Nov 2016

Focused-Based Multifractal Analysis Of The Wake In A Wind Turbine Array Utilizing Proper Orthogonal Decomposition, Naseem Ali, Hawwa Falih Kadum, Raúl Bayoán Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

Hot-wire anemometry measurements have been performed in a 3×3 wind turbine array to study the multifractality of the turbulent kinetic energy dissipation. A multifractal spectrum and Hurst exponents are determined at nine locations downstream of the hub height, bottom and top tips. Higher multifractality is found at 0.5D and 1D downstream of the bottom tip and hub height. The second order of the Hurst exponent and combination factor shows the ability to predict the flow state in terms of its development. Snapshot proper orthogonal decomposition (POD) is used to identify the coherent and incoherent structures and to reconstruct the stochastic …