HYBRID LARGE EDDY SIMULATION/LAGRANGIAN STOCHASTIC MODEL FOR TURBULENT PASSIVE AND REACTIVE SCALAR DISPERSION IN A PLANE JET

Abstract

A hybrid large eddy simulation (LES)-Lagrangian model is tested by computing passive and reactive scalar dispersion in inhomogeneous turbulent flows. Fluid particles are tracked in a Lagrangian way. In order to obtain the subgrid scale velocity component of fluid particles, a Lagrangian stochastic subgrid model is coupled at the subgrid scale level with the Eulerian LES. An additional pairing exchange model is used to take into account molecular diffusion. A second-order irreversible chemical reaction is considered to take place within each fluid particle. Validation is achieved by comparing the mixture fraction that behaves as a passive scalar to a passive scalar simulation. The results of the LES/Lagrangian modeling are compared with experimental results and with pure Eulerian LES where a passive scalar transport equation is solved. The objective of the work is to test the model and its ability to reproduce inhomogeneous reactive cases.

Keywords:

• Lagrangian approach
• Langevin model
• Large eddy simulation
• Reactive scalar
• Turbulent particle dispersion