Nonlinear Processes in Geophysics www.nonlin-processes-geophys.net 1023-5809 1607-7946 16 6 2009 10.5194/npg-16-677-2009 http://www.nonlin-processes-geophys.net/16/677/2009/ http://www.nonlin-processes-geophys.net/16/677/2009/npg-16-677-2009.html http://www.nonlin-processes-geophys.net/16/677/2009/npg-16-677-2009.pdf 677 690 2009-12-14 What determines size distributions of heavy drops in a synthetic turbulent flow? J. C. Zahnow zahnow@icbm.de U. Feudel Theoretical Physics/Complex Systems, ICBM, University of Oldenburg, 26129 Oldenburg, Germany We present results from an individual particle based model for the collision, coagulation and fragmentation of heavy drops moving in a turbulent flow. Such a model framework can help to bridge the gap between the full hydrodynamic simulation of two phase flows, which can usually only study few particles and mean field based approaches for coagulation and fragmentation relying heavily on parameterization and are for example unable to fully capture particle inertia. We study the steady state that results from a balance between coagulation and fragmentation and the impact of particle properties and flow properties on this steady state. We compare two different fragmentation mechanisms, size-limiting fragmentation where particles fragment when exceeding a maximum size and shear fragmentation, where particles break up when local shear forces in the flow exceed the binding force of the particle. For size-limiting fragmentation the steady state is mainly influenced by the maximum stable particle size, while particle and flow properties only influence the approach to the steady state. 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