Image processing using proper orthogonal and dynamic mode decompositions for the study of cavitation developing on a NACA0015 foil

Sébastien Prothin (1) , Jean-Yves Billard (2) , Henda Djeridi (3)

1 DAEP - Département Aérodynamique Energétique et Propulsion
2 IRENAV - Institut de Recherche de l'Ecole Navale
3 LEGI - Laboratoire des Écoulements Géophysiques et Industriels [Grenoble]

The purpose of the present study is to get a better understanding of the hydrodynamic instabilities of sheet cavities which develop along solid walls. The main objective is to highlight the spatial and temporal behavior of such a cavity when it develops on a NACA0015 foil at high Reynolds number. Experimental results show a quasi-steady, periodic, bifurcation domain, with aperiodic cavity behavior corresponding to σ/2α values of 5.75, 5, 4.3 and 3.58. Robust mathematical methods of signal postprocessing (proper orthogonal decomposition and dynamic mode decomposition) were applied in order to emphasize the spatio-temporal nature of the flow. These new techniques put in evidence the 3D effects due to the reentrant jet instabilities or due to propagating shock wave mechanism at the origin of the shedding process of the cavitation cloud.

Mots clés: NACA0015 foil; Signal postprocessing; Hydrodynamic instabilities

Domaines: Mécanique des fluides [physics.class-ph]

Sébastien Prothin, Jean-Yves Billard, Henda Djeridi. Image processing using proper orthogonal and dynamic mode decompositions for the study of cavitation developing on a NACA0015 foil. Experiments in Fluids, 2016, 57 (10), pp.157-182. ⟨10.1007/s00348-016-2246-1⟩. ⟨hal-01377045⟩