Lagrangian diffusion in a turbulent jet using Large-Eddy Simulation
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In a recent study, a stationarization method for the velocity along fluid particle trajectories was proposed, allowing the expansion of stationary Lagrangian theory to inhomogeneous, self-similar flows. The success of the methodology was demonstrated through the collapse of the Lagrangian streamwise second-order structure function, for a turbulent jet flow of Taylor Reynolds number in the order of 230 using laboratory data. In this study, the Large-Eddy Simulation (LES) of a similar flow was performed, including the simulation of passive tracers. Results of flow statistics such as mean velocity, variances and covariances, as well as the turbulence kinetic energy budget and Eulerian time-scale, compared well with the experimental data. The Lagrangian velocity of passive particles was stationarized using the local Eulerian mean velocity and time-scale, as proposed by the new method. The collapse of the Lagrangian streamwise second-order structure function after stationarization was obtained for additional streamwise positions and a broader range of scales compared to the original study. The LES dataset complements the laboratory data by providing additional flow field information, which will be used in a deeper investigation of the Lagrangian properties of particle dispersion in turbulent flows.
