Enstrophy Analysis of a Turbulent Temporal Plume

The aim of the present thesis work is to analyse the enstrophy behaviour of a temporal turbulent plume. Several previous works have focused their attention on the role of vorticity or enstrophy in free shear flows, but they mainly concentrate on jets, wakes or mixing layers. The analysis is performed on a temporal turbulent plume at time t = 40 which shows a Reλ= 89. The analyses performed start from a flow general features assessment. It is retrieved that the coherent vorticity structures inside a plume can be divided in Large Vorticity Structures (LVSs) and Intense Vorticity Structures (IVSs) and that the LVSs are responsible for the Turbulent/Non-Turbulent (T/NT) interface geometrical shape. In addition, the sensitivity to the enstrophy detection threshold is tested and verified retrieving a good interface robustness. The characteristics of the T/NT interface are analysed exploiting the traditional mean enstrophy budget equation and the conditional mean enstrophy budget equation.