Models for liquid droplet dynamics

Abstract

Aerosol is a suspension of solid or liquid particles in a gas. Determining the behaviour of aerosols is a complex and important problem. In this research I have done scientific computations for validating the FLACS code for describing aerosol phenomena. I have developed Fortran codes for droplet motion, evaporation, variation of Weber number of droplets, and droplet break up time, and compared these results with the results obtained from the FLACS simulation. The behaviour of decane droplet cloud of different diameters was simulated over realistic range conditions of temperature and concentration. I studied the droplets' motion; their interaction with the surrounding fluid, deformation, evaporation, secondary break up under various wind conditions and coalescence separately, so that each phenomenon could be understood fully without confounding mutual influence. Finally I compared these simulation results with theory and the available experimental data. The study focuses on the two-phase aspects, with emphasis on flash atomisation and droplet dynamics downstream. This research has also ascertained whether two phase modelling practice and philosophy adopted for the problem of accidental atmospheric dispersion releases of 'flashing' substances as utilized in the FLACS code is consistent and up to date with literature in the public domain. It has identified strengths and weaknesses of the current models and possible alternative modelling approaches. Finally, it provides clear recommendations.