Measurement and simulation of a droplet population in a turbulent flow field

The interaction of a disperse droplet population (spray) in a turbulent flow field has been investigated by combining wind tunnel experiments with simulations based on a population balance system. The behavior of the droplets is modeled numerically by a population balance equation. Velocities of the air and of the droplets are determined by non-intrusive measurements. A direct discretization of the 4D equation for the droplet size distribution is used in the simulations. Important components of the numerical algorithm are a variational multiscale method for turbulence modeling, stabilized finite difference schemes for the 4D equation and a pre-processing approach to evaluate the collision integrals. The simulations of this system accurately predict the modifications of the droplet size distribution from the inlet to the outlet of the measurement section. Since the employed configuration is simple and considering that all measurement data are freely available thanks to an internet-based repository, the considered experiment is proposed as a benchmark problem for the simulation of disperse two-phase turbulent flows.

► Disperse two-phase flows are essential for many applications.
► Combined experimental/numerical investigations are particularly revealing.
► Direct discretization of the 4D equation describing droplet size distribution.
► Collision integrals are precomputed in a numerically efficient manner.
► First comparisons show a good agreement with experimental data.