COLLAPSE, INTENSIFICATION AND RECONNECTION IN VORTEX DOMINATED FLOWS - VISIOMETRICS AND MODELING

We study collapsing vortex configurations via the visiometrics approac h, which consist of the implementation of quantitative diagnostics sup ported by scientific visualization techniques. The computation of the strain-rate in a ''diagnostics box'' surrounding the collapse regions reveals that the largest strain-rate amplification is off the vortex t ubes. The location and orientation of the maximum strain-rate coincide s with the incipient ''bridge'' formation in vortex reconnection. We a lso obtain a closer appreciation of the dominant coherent vortex struc tures in numerical simulations of Navier-Stokes turbulence by using fe ature extraction and feature tracking techniques.