Simulation of jet turbulence in the region of flow establishment

Abstract

In the present project, we aim to perform a numerical simulation of a round jet at Mach number 0.9, and at a Reynolds number about 10,000 in order to describe in detail the turbulence properties in the region of jet flow-establishment. This region extends from the jet initial mixing layers up to the jet self-similarity region, where the the jet turbulence is fully established. The second and third-order moments of velocity, the velocity-pressure correlations, and the balance of the turbulence energy will in particular be calculated directly from the computational unsteady fields. This should allow us to provide reference data which cannot be obtained experimentally, and to clarify the role of the different mechanisms in producing and redistributing the turbulent energy within the jet. To reach a high accuracy, the computation will be performed using finite-difference schemes with low-dissipation, and will require a high computational cost. The number of grid points will indeed be very large because of the jet Reynolds number considered, and also because of the physical need for discretizing thin initial jet mixing layers (typically of one per cent of the jet diameter). The simulation times will be also long for ensuring the convergence of the turbulence statistics.