Global self-excited oscillations in a two-dimensional heated jet : a numerical simulation

Abstract

The aim of this work was to develop a numerical methodology to gain insight in the low-density jet behaviour with a nonlinear approach. Numerical simulations are shown to differentiate convective and absolute instability regimes and to capture a self-excited global mode in an open flow : the 2D hot jet. The first part is devoted to numerical methodology and its validation on this unsteady problem which is known to be noise sensitive. The second part presents numerical results. They confirm theoretical and experimental results on the development of self-exited global oscillations of the jet column when the density ratio is lower than its critical value. The global mode and its associated Hopf bifurcation are identified.