A confined turbulent round jet immersed in an arrangement of annular jets, called port-array, is studied numerically. The objective is to evaluate numerically the effect of annular jets in the structure of the turbulence in the central jet. Three-dimensional large eddy simulation technique is used for turbulence modelling. In order to analyze the state of the turbulence, anisotropy invariant map and novel 3D-anisotropy invariant map are used. Results show earlier transition to turbulence in the central jet by the effect of annular jets. At the same time, the annular jets modify the structure of the turbulence of the central jet, thereby the mean spanwise fluctuations begin to be more important and intense. The transport of the properties due to the intensification in these fluctuations improves the mixing process.

port-array, confinement, mixing, LES, invariant analysis.