Środowiskowe Seminarium Fizyki Atmosfery

Recent studies attribute evolution of droplet size distribution in warm convective clouds to enhancement of collision-coalescence by turbulence. This seminar has an aim to present studies of preferential concentration, which may lead to enhanced collisions. The main part of a presentation demonstrate droplet motion in vortex tubes - small coherent structures characteristic for high Reynolds number turbulent flows. Former research of such effects was limited to horizontally oriented vortex tubes only. Herein we analysed tubes approximated by point vortices of axes parallel or oblique to the direction of gravity. Both analytical and numerical solutions of Stokes equation used in our study as a droplet equation of motion allowed to identify features such as stationary points, stationary orbits and limit cycles, which may influence preferential concentration. A short overview of the experiment conducted this autumn in so called „Barrel of Ilmenau” at TU Ilmenau in Germany, aimed at verification of preferential concentration of droplets in homogeneous turbulence will be given in the last part of the talk.