TOPOLOGICAL VISUALIZATION OF FOCAL STRUCTURES IN FREE SHEAR FLOWS

This paper describes a method for identifying and visualising the thre e-dimensional geometry of focal (vortex) structures in complex flows. The method is based primarily on the classification of the local topol ogy as it is identified from the values of the velocity gradient tenso r invariants. The identification of the local topology is reference fr ame invariant. Therefore, focal (vortex) structures can be unambiguous ly identified in these flows. A novel flow visualisation method is int roduced whereby focal structures are rendered using a solid model view of the local topology. This new approach is applied to the identifica tion of focal structures in three-dimensional plane mixing layer and p lane wake flows.