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| Dennis,David J.C.. |
| The inherent difficulty of understanding turbulence has led to researchers attacking the topic in many different ways over the years of turbulence research. Some approaches have been more successful than others, but most only deal with part of the problem. One approach that has seen reasonable success (or at least popularity) is that of attempting to deconstruct the complex and disorganised turbulent flow field into to a set of motions that are in some way organised. These motions are generally called "coherent structures". There are several strands to this approach, from identifying the coherent structures within the flow, defining their characteristics, explaining how they are created, sustained and destroyed, to utilising their features to model the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Turbulence; Wall bounded flows; Coherent structures; Particle image velocimetry. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652015000201161 |
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| Bouhoubeiny, Elkhadim; Druault, Philippe. |
| To enhance the temporal resolution of the PIV measurements of pseudo-periodic turbulent flows, Proper Orthogonal Decomposition (POD) has been previously used to time interpolate PIV database. In this note, it is demonstrated that such POD interpolation is equivalent to the classical mathematical interpolation when dealing with the whole POD eigenfunctions, since POD is a linear transform. In fact, the POD-based time interpolation is only valid for the large scale structures of the flow. The advantage of using POD procedure resides in its efficiency in extracting the dominant flow structures. In this sense, other interpolation methods such as turbulent filtering procedures could provide similar results. To cite this article: E. Bouhoubeiny, P Druault, C R.... |
| Tipo: Text |
Palavras-chave: Fluid mechanics; Particle image velocimetry; Proper orthogonal decomposition; Large scale flow structures. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00021/13199/10314.pdf |
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| Dussol, David; Druault, Philippe; Mallat, Bachar; Delacroix, Sylvain; Germain, Gregory. |
| When performing Particle Image Velocimetry (PIV) measurements in complex fluid flows with moving interfaces and a two-phase flow, it is necessary to develop a mask to remove non-physical measurements. This is the case when studying, for example, the complex bubble sweep-down phenomenon observed in oceanographic research vessels. Indeed, in such a configuration, the presence of an unsteady free surface, of a solid–liquid interface and of bubbles in the PIV frame, leads to generate numerous laser reflections and therefore spurious velocity vectors. In this note, an image masking process is developed to successively identify the boundaries of the ship and the free surface interface. As the presence of the solid hull surface induces laser reflections, the hull... |
| Tipo: Text |
Palavras-chave: Particle image velocimetry; Unsteady free interface; Edge detection method; Morphological analysis. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00327/43778/43335.pdf |
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