A method to characterise jets using correlations of large-scale features in instantaneous planar images

Abstract

An approach to characterise jets by analysis of the locations of large-scale features identified in images of the instantaneous flow field is presented. A frequency domain is generated from the correlations of identified large-scale features in ensembles of instantaneous planar images. The frequency-domain correlation image provides a measure of the underlying large-scale features; namely the characteristic distances and angles between large-scale features, number densities of large-scale features in the image field, variations in distance between large-scale features and their dominant mode. The approach is assessed analytically and applied to experimental data. Results show that the proposed method can be used successfully to characterise the large-scale features of jet flows.