ESR1 - Transport across warm turbulent interfaces
  1. Numerical analysis by using Lagrangian Turbulence spectral solvers of the transport of energy, water vapour and droplets across the interface warm cloud/clear air in a stably and non-stably stratified environment.
  2. Lagrangian analysis of small inertial water droplets in suspension (1 -100 micron) across turbulent-non turbulent cloud interfaces and inside warm clouds.
  3. Inclusion of effects associated to buoyancy and condensation/evaporation.
ESR2 - Floating cloud radiosondes data analysis from in-field and laboratory experiments

Analysis of data produced by innovative expendable bio-compatible radio-probes released and floating in warm clouds. Comparison of field data with numerical simulations.

ESR3 - Interfacial dynamics of aerosols and droplets
  1. Study of particles (aerosols/droplets) in interfacial dynamics either in shear-free mixing layers where the interface is between two different turbulent intensity fields or in cases where the interface will be between a turbulent and a non-turbulent field.
  2. Study of interfaces as they appear in wakes and jets to simulate in the laboratory and the computer the kind of turbulent/non-turbulent interfacial physics which may be found in clouds under certain conditions.
ESR4 - The effect of buoyancy on the dynamics of aerosols and particles
  1. Numerical study (Direct Numerical Simulation) of the interaction between the flow interface and an approximately collocated buoyancy interface
  2. Influence of the nonlinear dependence of buoyancy on mixing fraction in clouds, and how these enhance/reduce turbulent exchange
  3. Dynamics of buoyant inertial particles
ESR5 - Drop dynamics in turbulent flows
  • Experimental measurement of the acceleration and relative velocity of micrometric droplets in warm clouds in situ at the research station Schneefernerhaus.
  • Numerical scheme capable of reproducing the experimental results.
ESR6 - Development of a droplet generator, drop collision measurement
  • To develop a drop generator capable of rapid creation of liquid droplets of sizes 5-50 µm, similar to those typically found in warm clouds.
  • To control also the initial velocity of the created drops, both in magnitude and direction.
  • Experimental measurement of the coalescence rate of droplets generated with the device.
ESR7 - Lagrangian properties of aerosol parcels at the turbulent/non-turbulent interfaces with density jumps

Experimental and numerical based estimates of "apparent diffusivity" of particles and fluid parcels crossing the turbulent/non-turbulent interfaces with density jumps.

ESR9 - Small-scale turbulence and spatial distribution of droplets in clouds

The project is aimed at joint investigation of droplet spatial distribution and small-scale turbulence in clouds. We plan to measure positions and velocities of cloud droplets in a two-dimensional plane enlightened by a laser sheet technique. We will build a device allowing for uniform illumination of cloud volume of the area ~50x50 cm2 and of variable thickness (~1mm to ~2cm).

ESR10 - Sub-grid scale modelling of particle transport in Large Eddy Simulations of fluid flows

The project is aimed at numerical modelling of transport and interactions of Stokes particles, such as cloud droplets and other aerosols (WP 3, 4). In high Reynolds number flows, say in a cumulus cloud, there is a gap of 2-4 decades between the Kolmogorov scale and the size of transported droplets. Therefore, even Direct Numerical Simulations of the flow require sub-grid scale (SGS) modelling to account for droplet transport and interactions within one grid cell.

ESR11 - Lagrangian estimates of enrtainment rates in clouds
  • Computing balloon Lagrangian trajectories from LES outputs in shallow cumulus and stratocumulus conditions.  
  • Comparison with data from mini radioprobes from WP2.
  • Specific adjustement to Lagrangian trajectories will have to be implemented to take into account balloon dynamics.
  • Rates of mixing will be estimated at the interfaces of cloudy and clear air.
ESR12 - Disposable radio-probes
  1. Testing on the field of the sensing probes.
  2. Pre-processing of data acquired by the ground station.
ESR13 - Investigation on the way to include water droplet heterogeneous nucleation classical and non-classical models inside direct numerical simulation codes describing turbulent mixing and entrainment at the boundary of a cloud

The aim is to propose numerical new procedures to implement droplet nucleation models inside codes where the cloud interface is studied by coupling the Eulerian description of the turbulent velocity and water vapour fields with a Lagrangian ensemble of cloud water droplets that can undergo stochastic nucleation, as well as growth and shrinking by condensation and evaporation, respectively.