DIRECT NUMERICAL SIMULATIONS OF TURBULENCE-CLOUDAEROSOL INTERACTIONS IN ATMOSPHERIC CLOUDS

Clouds play a critical role in the evolution and change of climate. However, their interaction with turbulent atmosphere is still a source of uncertainty. Direct numerical simulation (DNS) has become an indispensable tool to investigate the dynamics of atmospheric clouds. In this paper, a DNS model is presented that solves the governing equations for the flow of air, temperature, and water vapor mixing ratio in Eulerian fashion, assuming homogeneous and isotropic turbulence. Aerosol particles and cloud droplets are tracked using Lagrangian particle tracking method. Curvature and solute effects are included in our model, and the initial dry aerosol size distribution is assumed to be lognormal. By varying the intensity of flow turbulence, the mutual conversion of aerosol particles and cloud droplets is examined. The results indicate that a higher level of turbulence promotes the deactivation of cloud droplets into aerosol particles.