Lagrangian tracking of heavy particles in large-eddy simulation of turbulent channel flow

The problem of assessing accurate Eulerian-Lagrangian modeling of heavy particle dispersion in Large Eddy Simulation (LES) is addressed. This issue is investigated in a systematic way by performing a priori and a posteriori LES coupled with Lagrangian particle tracking of fully developed channel flow, in which different,rid resolutions and different, values of the particle response time are considered. The accuracy in the prediction of the. particle velocity statistics, near wall accumulation (turbophoresis) and preferential concentration is assessed trough comparison against DNS data. Both a priori and a posteriori tests indicate that turbophoresis and particle segregation can not be accurately predicted without introducing a model in die particle motion equations, also for particles having a response time much larger than the scales non resolved in LES. Furthermore, the present results indicate that. the reintroduction of the correct. level of fluid and particle velocity fluctuations is not the only issue for a closure model for particle equations.