Paths to caustic formation in turbulent aerosols

The dynamics of small, yet heavy, identical particles in turbulence exhibits singularities, called caustics, that lead to large fluctuations the spatial particle-number density, and collision velocities. For particle, inertia fluid velocity at particle position is essentially a white-noise signal caustic formation analogous Kramers escape. Here we show small different. Caustics tend form vicinity trajectories experience specific history fluid-velocity gradients, characterised by low vorticity violent strain exceeding threshold. We develop theory explains our findings terms an optimal path approached limit.