Sardina Gaetano, Picano Francesco, Brandt Luca, Caballero Rodrigo
Department of Meteorology and SeRC, Stockholm University, SE-106 91 Stockholm, Sweden.
Linné FLOW Centre and SeRC, KTH Mechanics, SE-100 44 Stockholm, Sweden.
Phys Rev Lett. 2015 Oct 30;115(18):184501. doi: 10.1103/PhysRevLett.115.184501. Epub 2015 Oct 29.
We use a stochastic model and direct numerical simulation to study the impact of turbulence on cloud droplet growth by condensation. We show that the variance of the droplet size distribution increases in time as t^{1/2}, with growth rate proportional to the large-to-small turbulent scale separation and to the turbulence integral scales but independent of the mean turbulent dissipation. Direct numerical simulations confirm this result and produce realistically broad droplet size spectra over time intervals of 20 min, comparable with the time of rain formation.
我们使用随机模型和直接数值模拟来研究湍流对云滴通过凝结增长的影响。我们表明，液滴尺寸分布的方差随时间以t^{1/2}的形式增加，其增长率与大尺度到小尺度的湍流尺度分离以及湍流积分尺度成正比，但与平均湍流耗散无关。直接数值模拟证实了这一结果，并在20分钟的时间间隔内产生了逼真的宽液滴尺寸谱，这与降雨形成的时间相当。
