A particle-based direct numerical simulation model for turbulence-cloud-aerosol interactions

Understanding aerosol-cloud interactions and their representation in weather and climate models is challenging. Previous efforts such as the development of the global climate models, numerical weather prediction, and large eddy simulation (LES), are not able to represent vital processes that occur at spatial scales smaller than the typical grid sizes used in these models. These processes include cloud and aerosol microphysics, turbulent entrainment-mixing between clouds and environmental air, and turbulence-cloud-aerosol interactions. In this work, we are developing a particle-based direct numerical simulation model that resolves the smallest turbulent eddies in the cloud, tracks physical evolution of individual cloud and aerosol particles, and covers a domain that is comparable to those that have been simulated with LES. Cloud and aerosol number densities and their particle size spectra are the key parameters being evaluated. The comparative effects of different sources of aerosol, such as fossil fuels, biomass, sea salt, and dust, are being investigated. The FronTier fluid dynamic software package is being used for the analysis. Parallelization is achieved via the MPI protocol, with the domain decomposition technique. The implications of the simulation results for weather and climate change are studied.