Investigation of turbulent mixing using a stochastic hierarchical parcel swapping mixing model

Turbulent mixing plays an important role in a variety of applications ranging from astrophysics to combustion and even pollutant dispersion. The Direct Numerical Simulation (DNS) that resolves all scales is not feasible for most engineering since the flow has wide range length time scales, which yields extremely high resolution requirements. Large Eddy Simulations (LES) overcome this limitation by modeling sub-grid scale effects. In transported Probability Density Function (PDF) methods, key challenge develop accurate model. At point, Hierarchical Parcel-Swapping (HiPS) model, introduced A.R. Kerstein [J. Stat. Phys. 153, 142-161 (2013)], attractive candidate. It characterized computationally efficient representation effects turbulence on time-evolving structure diffusive scalar fields. interpretation fields or state space as binary tree alternative approach compared common models. characteristic feature HiPS every level corresponds specific scale, based inertial scaling. variables only reside at base are understood fluid parcels. turbulent advection represented stochastic swaps sub-trees rates determined prevailing associated with sub-trees. adjacent parcels done either instantaneously consistent corresponding diffusion scales. work, detailed simulation passive first. Preliminary results power spectra, mean square displacement dissipation rate shown reveal reasonable agreement experimental findings. Furthermore, integrated allows satisfy large number criteria good Considering reduced order computational efficiency, candidate PDF methods.