IGF



Environmental Atmospheric Physics Seminar

LACIS-T - A moist air wind tunnel for investigating the interactions between turbulence and cloud microphysics

dr Dennis Niedermeier

Leibniz Institute for Tropospheric Research, Leipzig, Germany

 

Oct. 11, 2019, 1:15 p.m., ul. Pasteura 5, B0.14

The interactions between turbulence and cloud microphysical processes have been investigated primarily through numerical simulation and field measurements over the last ten 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 this talk, a unique turbulent moist-air wind tunnel will be presented, called the Turbulent Leipzig Aerosol Cloud Interaction Simulator (LACIS-T) which has been developed in order to study cloud physical processes in general and interactions between turbulence and cloud microphysical processes in particular. 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 time (up to a few seconds) and spatial scales (micrometer to meter scale) and with a Lagrangian perspective. The experimental studies using LACIS-T are accompanied and complemented by Computational Fluid Dynamics (CFD) simulations which are helpful to design experiments as well as to interpret experimental results.
In this talk, I will present the fundamental operating principle of LACIS-T, the numerical model as well as results concerning the thermodynamic and flow conditions prevailing inside the wind tunnel combining both characterization measurements and numerical simulations. Finally, results are depicted from deliquescence/hygroscopic growth as well as droplet activation and growth experiments.


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