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Chen X.,Laboratoire Of Mecanique Des Fluides Et Dacoustique | Zille P.,Laboratoire Of Mecanique Des Fluides Et Dacoustique | Shao L.,Laboratoire Of Mecanique Des Fluides Et Dacoustique | Corpetti T.,Laboratoire COSTEL UMR 6554 LETG
Experiments in Fluids | Year: 2015

We propose in this paper a new formulation of optical flow dedicated to 2D incompressible turbulent flows. It consists in minimizing an objective function constituted by an observation term and a regularization one. The observation term is based on the transport equation of the passive scalar field. For non-fully resolved scalar images, we propose to use the mixed model in large eddy simulation to determine the interaction between large scales and unresolved ones. The regularization term is based on the continuity equation of 2D incompressible flows. Compared to prototypical method, this regularizer preserves more vortex structures by eliminating constraints over the vorticity field. The evaluation of the proposed formulation is done over synthetic and experimental images, and the improvements in term of estimation are discussed. © 2014, Springer-Verlag Berlin Heidelberg.

Mancinelli M.,Third University of Rome | Pagliaroli T.,Third University of Rome | Di Marco A.,Third University of Rome | Camussi R.,Third University of Rome | And 3 more authors.
22nd AIAA/CEAS Aeroacoustics Conference, 2016 | Year: 2016

An experimental study of the pressure fluctuations generated by a single-stream subsonic isothermal jet has been carried out. Measurements were performed for two jet Mach numbers in an anechoic wind tunnel using a linear microphone array in the near field and a polar microphone array in the far field. The main focus of the present investigation was the analysis of the near-field pressure data. Three novel decomposition techniques for the separation of the hydrodynamic and acoustic pressures in the near field based on wavelet transform are presented. The innovative techniques were validated by the comparison with separation procedures found in the literature. Hydrodynamic and acoustic pressures were characterized in terms of spectral content and statistical quantities, establishing a direct link between acoustic pressure in the near field and noise measured in the far field. The effect of the stream-wise position of the near-field microphone as well as of the jet Mach number were clearly addressed. The analysis shed light on the intermittent/nearly Gaussian nature of the hydrodynamic/acoustic component. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

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