Identification of Vortex Structures in A Coaxial Jet

Abstract

This work examines some methods used to identify vortex structures in a coaxial compressible jet flow simulated by the 3D model (LES). The majority of these methods focus on the definition of vortices. The delta-criterion, lambda2-criterion, Q-criterion, and omega-criterion methods are considered among the most common local Eulerian vortex identification methods, based on local point analysis velocity gradient. Moreover, the delta-criterion, lambda2-criterion, and Q-criterion, vortex identification methods require selecting an appropriate criterion threshold. In contrast, the new Omega method can capture both strong and weak vortices without adjustment. Acomparative study of the different vortex identification methods was carried out to use the criterion that seems to be the most appropriate for the case study. The results show that the omega criterion identifies vortex structures more accurately than the other criteria.