Bottleneck for particle collisions in turbulent aerosols KAW kickoff meeting Stockholm node (AB,DM, a postdoc)

Coagulation-condensation Smoluchowski equation: Zero dimension, binary collisions. evaporation Coagulation Fragmentation Condensation

Smoluchowski-Boltzmann (SB eqn.) Generalize to d-dimensions: (for no external foce) This is exactly like the Boltzmann eqn. but with the collision kernel of Smoluchowski type.

SB equation: Method 1 Take hydrodynamic limit via Chapman-Enskog expansion. The solve the resultant eqns. with pencil-code.

SB equation: Method 2 Solve the SB eqn. numerically using Lattice Boltzmann Method (LBM) Velocities are discretized on a lattice; D2Q9 in 2d, D3Q19 in 3d. The Smoluchowski collision kernel need to be implemented in a LBM code (possible collaborations with P. Perlekar)

Method 3: Lagrangian approach Solve the Navier-Stokes equations using the pencil-code with particles. For particles, solve for heavy particles whose drag depends on their radius which in turn depends on their mass. Take into account collisions between the particles and resultant merging, and break-up. (particles_potential module, work-in-progress, collaborations with N. Heigen)

Fine prints The coagulation and fragmentation kernel will depend on collisional velocities, enviroment (e.g., temperature), on whether we are dealing with raindrops or dust grains. This is a material science problem. But many details of the kernel may be lost by the CE expansion. Can we assume the dust to be at thermal equilibrium with local fluid ?

Administrative details Hiring a postdoc to work at the Stockholm node on the lines described above. We expect the postdoc to start in the fall of 2015, for two years, extendable by another year. We would like to start advertising as soon as possible.