Formation of zones of an inverse energy cascade in an axisymmetric jet

Abstract

The results of investigation into the mechanism of formation of an inverse turbulence energy cascade in an axially symmetric submerged jet based on numerical modeling by the large eddy simulation. The flow structure is calculated using two models of subgrid turbulence in a broad range of Reynolds numbers with the imposed external harmonic low-amplitude perturbation and swirling. Calculations showed that upon imposing swirling, the effect of formation of the inverse cascade is suppressed, while upon imposing the external low-amplitude harmonic perturbations corresponding to the frequency of highest perceptivity, it is enhanced. We can assume that the regions with the inverse turbulence energy flow are formed there where the dynamics of large quasi-2D structures is determined by the mechanisms of combining eddies and involvement processes, while the tension mechanism of vortex tubes is suppressed. It is shown that the balance of these mechanisms can be controlled by means of imposition of low-amplitude harmonic perturbations.