Direct numerical simulations of finite-thickness cross sections of jets

Direct numerical simulations (DNS) of turbulence have been performed extensively using homogeneous isotropic turbulence in a triply periodic cubic domain. However, turbulent flows in practical applications involve shear flows like turbulent round jets, simulating which would be computationally expensive. Instead, a new framework for simulating turbulent jets is proposed, wherein a portion of the jet is emulated with a "disk" of finite thickness, that is periodic in the axial direction. The analysis uses the self-similarity of turbulence in jets, and implements corresponding normalizations for velocity components and spatial coordinates. Both non-reacting and reacting flows are considered, and the velocity fluctuations are calculated and compared with that of experimental turbulent jets. The turbulent kinetic energy budget is computed and compared with the budget from other simulations and experiments. For the reacting case, the flame structure is observed and the flame surface area and turbulent flame speed are calculated and compared with results from previous large eddy simulations and experimental results of turbulent reacting jets.