Cooling driven coagulation

Abstract Astrophysical gases such as the interstellar-, circumgalactic- or intracluster-medium are commonly multiphase, which poses question of structure these systems. While there many known processes leading to fragmentation cold gas embedded in a (turbulent) hot medium, this work, we focus on reverse process: coagulation. This is often seen wind-tunnel and shearing layer simulations, where fragments spontaneously coalesce. Using 2D 3D hydrodynamical find that sufficiently large (≫cstcool), perturbed clouds develop pulsations ensure mass growth over an extended period time (≫r/cs). efficiently accelerates turn can entrain droplets, The attractive inverse square force between droplets has interesting parallels with gravity; ‘monopole’ surface area rather than mass. We simple analytic model reproduces our numerical findings.