Application of DNS and LES to Dispersed Two-Phase Turbulent Flows

An overview and examples of the application of Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) to prediction and the scientific study of dispersed, turbulent two-phase flows is presented. This contribution focuses on Eulerian-Lagrangian treatments in which dispersed phase properties are obtained from discrete particle trajectories. The scope of the approaches considered are on systems in which the ensemble comprising the particulate phase is large enough that direct resolution of the flow in the vicinity of each particle is not feasible and, consequently, models of particle dynamics must be imposed. The advantages and limitations of each technique are first considered, representative applications of both DNS and LES to “building block” flows are then summarized: statistically stationary particle-laden isotropic turbulence and fully-developed turbulent channel flow. In both flows, the detailed descriptions possible using DNS and LES enable in-depth evaluations of statistical and structural features. The specific properties considered including the role of inter-particle collisions in turbulent channel flow and more recent efforts focused on exploration and analysis of the spatial structure of the particle velocity field.