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Abstract. The interactions between turbulence and cloud microphysical processes have been investigated primarily through numerical simulation and field measurements over the last 10 years. However, only in the laboratory we can be confident in our knowledge of initial and boundary conditions and are able to measure under statistically stationary and repeatable conditions. In the scope of this paper, we present a unique turbulent moist-air wind tunnel, called the Turbulent Leipzig Aerosol Cloud Interaction Simulator (LACIS-T) which has been developed at TROPOS in order to study cloud physical processes in general and interactions between turbulence and cloud microphysical processes in particular. The investigations take place under well-defined and reproducible turbulent and thermodynamic conditions covering the temperature range of warm, mixed-phase and cold clouds (25∘C>T>-40∘C). The continuous-flow design of the facility allows for the investigation of processes occurring on small temporal (up to a few seconds) and spatial scales (micrometer to meter scale) and with a Lagrangian perspective. The here-presented experimental studies using LACIS-T are accompanied and complemented by computational fluid dynamics (CFD) simulations which help us to design experiments as well as to interpret experimental results. In this paper, we will present the fundamental operating principle of LACIS-T, the numerical model, and results concerning the thermodynamic and flow conditions prevailing inside the wind tunnel, combining both characterization measurements and numerical simulations. Finally, the first results are depicted from deliquescence and hygroscopic growth as well as droplet activation and growth experiments. We observe clear indications of the effect of turbulence on the investigated microphysical processes.

The efficiency of dry powder inhalers (DPIs) for drug delivery is still very low and is therefore the objective of intensive research. Thus, numerical calculations (computational fluid dynamics (CFD)) using the Euler/Lagrange approach without coupling are being performed in order to analyze flow structure and carrier particle motion within a typical inhaler device. These computations are being performed for a steady-state situation with a flow rate of 100 l/min. Essential for the detachment of the very fine drug powder (i.e., between 1 and 5 μm) from the carrier particles are the fluid stresses experienced by such particles (i.e., relative velocity, turbulence, and fluid shear) as well as wall collisions, which are both evaluated in the present study. Since the carrier particles are rather large (i.e., normally 50–100 μm), first the importance of different relevant fluid forces, especially transverse lift forces, is investigated. Moreover, the significance of the parameters in the particle–wall collision model is highlighted and a statistical analysis of particle–wall collisions in an inhaler is conducted. The improved understanding of particle motion in the normally very complex flows of inhalers will be the basis for optimizing inhaler design.

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