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ISSN オンライン: 2642-0554

DYNAMICS OF A TURBULENT BOUNDARY LAYER OVER CUBICAL ROUGHNESS ELEMENTS: INSIGHT FROM PIV MEASUREMENTS AND POD ANALYSIS

Laurent Perret
Laboratoire de Mecanique des Fluides, Ecole Centrale de Nantes, UMR CNRS 6598 1 rue de la Noe BP 92101, F-44321 Nantes Cedex 3, France

Cedric Rivet
LUNAM Universite, Ecole Centrale de Nantes LHEEA - UMR CNRS 6598 1 rue de la Noe, BP 92101, F-44321 Nantes Cedex 3, France

要約

The dynamics of the turbulent boundary layer developing over a cube array is analysed using stereoscopic PIV measurements performed in an atmospheric wind tunnel. The longitudinal component u of the velocity is analysed via the snapshot POD. It is first demonstrated that the first POD mode of u corresponds to large-scale elongated coherent structures of low- or high-speed which are non-negligible contributors to the shear-stress and the turbulent kinetic energy. Their relationship with the smaller scales of the flow is investigated via the computation of one- or two-point third order statistics and is shown to be of non-linear nature.