Waltz of tiny droplets and the flow they live in
S. Ravichandran, Rama Govindarajan
Abstract
The formation of raindrops in clouds requires the collision and coalescence of water droplets. The rapidity of this process has long been a puzzle in atmospheric fluid dynamics. We review one possible explanation - inertial particle caustics around strong vortices. We apply this simple physical picture to data from direct numerical simulations of highly turbulent flow, and show that caustics around vortices can, at high Reynolds number, provide the seed for the rapid formation of larger droplets, and thus rain, in ice-free clouds.
Topics & Concepts
Coalescence (physics)VortexMechanicsTurbulenceReynolds numberPhysicsCollisionFlow (mathematics)MeteorologyBreak-UpClassical mechanicsComputer scienceAstrobiologyComputer securityParticle Dynamics in Fluid FlowsAeolian processes and effectsAtmospheric aerosols and clouds