Particles in Turbulence: from tracers to rain form.. (PTurb)
Particles in Turbulence: from tracers to rain formation
Start date: Jun 15, 2009,
End date: Jun 14, 2011
In this project, we propose to experimentally study the behavior of particles in high Reynolds number turbulent flows in an unprecedented and challenging way. To address this general topic, we will combine two of the best modern experimental techniques used to track 3‐D particle motion: Tomographic Particle Image Velocimetry (T‐PIV), and Particle Tracking Velocimetry (PTV). The T‐PIV (cutting edge technology, developed in collaboration with LaVision gGmbH) will be used to track passive tracer particles, giving us the 3‐D Eulerian flow field. On the other hand, PTV will allow us to measure the Lagrangian trajectories of different types of particles evolving in the same part of the flow. We will observe flows in different forcing geometries, from highly anisotropic to nearly homogenous. We will use classical polystyrene or glass particles (that can have various sizes and densities), but we will also use "superparamagnetic" particles (designed in collaboration with INM Leibniz‐Institut fuer Neue Materialien gGmbH) in order to mimic the gravitational field g and vary its strength while keeping all other variables fixed. This will allow us to investigate certain aspects of cloud dynamics and rain formation. For the first time, quantitative measurements of the instantaneous flow field, together with Lagrangian tracks of particles with different properties, will be obtained simultaneously, at high Reynolds numbers. This will allow us to disentangle the complex coupling between particles and a turbulent flow by gauging the different terms in the Maxey & Riley equation (1983). These results could lead to a substantial improvement of the numerical simulations dealing with those problems by suggesting the correct approximations that must be done on the governing equation (or an ersatz), in order to stay realistic without increasing the computational time to infinity.
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