SPRAY DROPLET MODELING .1. LAGRANGIAN MODEL SIMULATION OF THE TURBULENT TRANSPORT OF EVAPORATING DROPLETS

The investigation of aerosol production and transport over the world's oceans is of importance in studies concerning cloud physics, air pollution, atmospheric optics, and air-sea interaction in general. However, the contribution of sea spray droplets to the transfer of moisture and latent heat from the sea to the atmosphere is not well known. In light of this, the Humidity Exchange Over the Sea Experiment in Simulation Tunnel and Couche Limite Unidimensionelle Stationnaire d'Embrums (one dimensional stationary droplet boundary layer) programs were designed to investigate the generation, turbulent transport, and evaporation of droplets ejected by bursting bubbles within the air-sea simulation tunnel at Institut de Mecanique Statistique de la Turbulence (IMST), Luminy, France. This first part describes the Lagrangian model developed as part of these programs to simulate the turbulent transport of evaporating droplets. The model relies on a form of the Langevin equation, which has been modified to account for the effects of gravity and the inertia of the droplets. The comparisons between the model and measurements show good agreement, particularly within the surface layer at IMST. Part 2 will describe the coupling of the model with an Eulerian k-epsilon model, which allows for improved simulation of the velocity and scaler fields, as well as a means for interaction between the droplets and these fields. The model is designed to provide a better understanding of the influence of these droplets on the near surface energy budget.