Comparison between the Q criterion and Rortex in the application of an in-stream structure

Abstract

A newly proposed vortex identification method, namely, Rortex, is used to visualize the vortex structures around an in-stream deflector with a large eddy simulation. A comparison with the well-known vortex identification method, the Q criterion, indicates that the Q criterion and Rortex can both capture the main vortex structures in the flow field. However, both the modified Q criterion and the wavelet analysis reveal that Rortex excludes the shear information on the deposited sand surface, while the Q criterion cannot. As a result, Rortex is more suitable for vortex identification.