Flow analysis of an annular jet by particle image velocimetry and properorthogonal decomposition

Abstract

This paper discusses the application of proper orthogonaldecomposition (POD) to the particle image velocimetry (PIV) velocity fields of the recirculation zone of anannular jet. The annular jet is an example of complex shear flow situations.Two axisymmetrical shear layers, originating at the exit of the jet, one at thelip of the nozzle and the other in the centre of the body, eventually meet downstream or interactwith each other. In this study we propose use of the POD on PIV velocityfields of the recirculation zone of this annular jet. According to PODanalysis, the primary objective of this paper is to describe the mode effectson the understanding of the nature of the flow and especially the linkbetween the first eigenfunctions of POD and the motion of the stagnationpoint at the extremity of the recirculation zone of the annular jet. Inparticular,this allows us to dissociate the oscillation and velocity fluctuations due to theturbulent flow behaviour.