Scalar Mixing Study at High-Schmidt Regime in a Turbulent Jet Flow Using Large-Eddy Simulation/Filtered Density Function Approach

Mixing of a passive scalar in a high-Schmidt turbulent round jet was studied using large-eddy simulation (LES) coupled to filtered density function (FDF). This coupled approach enabled the solution of the continuity, momentum, and scalar (concentration) transport equations when studying mixing in a confined turbulent liquid jet discharging a conserved scalar (rhodamine B) into a low-velocity water stream. The Monte Carlo method was used for solving the FDF transport equation and controlling the number of particles per cell (NPC) using a clustering and splitting algorithm. A sensibility analysis of the number of stochastic particles per cell as well as the influence of the subgrid-scale (SGS) mixing time constant were evaluated. The comparison of simulation results with experiments showed that LES/FDF satisfactorily reproduced the behavior observed in this flow configuration. At high radial distances, the developed superviscous layer generates an intermittency phenomenon leading to a complex, anisotropic behavior of the scalar field, which is difficult to simulate with the conventional and advanced SGS models required by LES. This work showed a close agreement with reported experimental data at this superviscous layer following the FDF approach.