A large eddy simulation study of mixing and intermittency of a coaxial turbulentjet discharging into an unconfined domain has been conducted. The work aims togain insight into the mixing and intermittency of turbulent coaxial jetconfigurations. The coaxial jet considered has relatively high jet velocitiesfor both core and annular jets with an aspect ratio (core jet to annular jet) of1.48. The computations resolved the temporal development of large-scale flowstructures by solving the transport equations for the spatially filtered mass,momentum and passive scalar on a non-uniform Cartesian grid and employed thelocalized dynamic Smagorinsky eddy viscosity as a sub-grid scale turbulencemodel. The results for the time-averaged mean velocities, associated turbulencefluctuations and mean passive scalar fields are presented. The initial inner andouter potential cores and the shear layers established between two cores havebeen resolved, together with the establishment of high turbulence regionsbetween the shear layers. The passive scalar fields developing from the core andthe bypass flow were found to exhibit differences at near and far fieldlocations. Probability density distributions of instantaneous mixture fractionand velocity have been created from which intermittency has been calculated andthe development of intermittency from the probability density distributions forinstantaneous velocity follows similar variations as for the passive scalarfields.
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