Dynamics of POD Modes in Wall Bounded Turbulent Flow

Alfonsi, Giancarlo; Primavera, Leonardo

doi:10.1007/11758501_64

Cited by 2 publications

(1 citation statement)

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“…The KL technique is optimal for modeling or reconstructing a signal in the sense that, for a given number of modes, the projection into the subspace used for modeling contains the most kinetic energy possible on average, or, equivalently, the decay of the tail of the empirical eigenspectrum is always faster (or at most as fast) than the tail of the spectrum based on any other possible basis, Fourier spectrum included. This technique has proven to give rather satisfactory results in several different cases (Alfonsi and Primavera [74][75][76][77], Alfonsi et al [78][79][80], Carbone et al [81], Vecchio et al [82], and Zhang et al [83]). …”

Section: Overview Of Karhunen-loève Decomposition Techniquementioning

confidence: 99%

Numerical Simulations of Wave-Induced Flow Fields around Large-Diameter Surface-Piercing Vertical Circular Cylinder

Alfonsi

2015

Computation

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A computational analysis is performed on the diffraction of water waves induced by large-diameter, surface-piercing, vertical circular cylinder. With reference to linear-wave cases, the phenomenon is preliminarly considered in terms of velocity potential, a simplified theoretical framework in which both hypotheses of inviscid fluid and irrotational flow are incorporated. Then, and as a first-approximation analysis, the Euler equations in primitive variables are considered (a framework in which the fluid is still handled as inviscid, but the field can be rotational). Finally, the real-fluid behavior is analyzed, by numerically integrating the full Navier-Stokes equations (viscous fluid and rotational field) in their velocity-pressure formulation, by following the approach of the Direct Numerical Simulation (DNS, no models are used for the fluctuating portion of the velocity field). For further investigation of the flow fields, the swirling-strength criterion for flow-structure extraction, and the Karhunen-Loève (KL) decomposition technique for the extraction of the most energetic flow modes respectively, are applied to the computed fields. It is found that remarkable differences exist between the wave-induced fields, as derived within the different computing frameworks tested.

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