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Heavy particles in turbulent flows

Project Acronym HEAVY
Scientific Discipline Fluid Dynamics
Principal Investigator(s) Dr Federico Toschi (Istituto per le Applicazioni del Calcolo - CNR)
Leading Institution IAC - CNR, Roma, Italy
Partner Institution(s)
  • INLN CNRS , Nice, France
DEISA Home Site CINECA

Project summary and results

The evolution of impurities and micro-droplets in a turbulent environment is an issue of great interest for a variety of applications ranging from health care to engineering and atmospheric sciences. Lagrangian tracking of particles in fully developed turbulent flows is an experimental challenge. State-of-the-art numerical simulations can at present permit "in silico" experiments in a range of parameters comparable with laboratory experiments. In the context of the DEISA project HEAVY, we performed state-of-the-art numerical simulations to study the Lagrangian evolution and the statistical properties of small particles/droplets transported by an incompressible homogeneous and isotropic turbulent flow. We tracked the evolution of billions of particles evolved by means of high-resolution (20483) pseudo-spectral fully-dealiased direct numerical integration of the Navier-Stokes equations. Data produced are currently being analyzed to study, in a systematic way, the effects of inertia on the preferential concentration and on the dynamics. The high resolution of our simulation allow us to study with high spatial and statistical resolution wild events like the ones associates with vortex trapping (see Figure 1). After an initial period of data analysis, we will share the raw data of our simulation with the whole international scientific community (visit iCFDdatabase for more information).

 

Figure 1. Trajectories of particles with different inertia, released from the same spatial position. The red curve is a particle with no inertia (fluid element, hence following the fluid material lines); the yellow curve is a particle with the largest inertia in our simulation. As the mass grows, particles are less and less sensitive to small scale vorticity and to rapid velocity variations; particles with high inertia are expelled from high vorticity regions.

Details on the numerical simulation performed

  • Number of particles integrated : 2.139.648.000
  • Numerical resolution of Eulerian field: 20483
  • Number of CPU: 512 @ SGI Altix 4700 - LRZ
  • CPU-hours (IBM SP4 1.3Ghz equivalent): 800.000
  • Wall-clock duration of project runs: 4 months
  • Maximal space on disk: 100Tbytes Final file formats: HDF5

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