Investigation of Turbulent Entrainment-Mixing Processes by Combining Measurements, DNS model and Parcel Model

Despite decades of research, our understanding of turbulent entrainment-mixing processes and their effects on cloud microphysics are still very limited. Their parameterizations in atmospheric models such as LES and climate models are barely started, and much remains to be learned. This study focuses on three topics related to turbulent entrainment-mixing processes by integrating observational analysis, parcel model simulations, and a new particle-resolved three-dimensional direct numerical simulation model that combines Lagrangian droplet tracking with the Eulerian field representation of turbulence near the Kolmogorov microscale. First, we will examine the three commonly used time scales (phase relaxation time, evaporation time and reaction time) in study of entrainment-mixing processes, and identify the appropriate conditions to use each of them. Second, we will examine the scale-dependence of entrainment-mixing processes under a variety of conditions. Finally, we will explore the parameterization of turbulent entrainment-mixing processes for atmospheric models. A new scale-aware parameterization will be presented according to the combined analysis.