2012/06/04 by Michael W. Reeks, Reeks, Michael W., Luca Fabbro +3
Engineering · #Cyclone Separators and Fluid Dynamics #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Turbulent Flows #Particle Dynamics in Fluid Flows
paper · pdf · doi:10.48550/arxiv.1206.0572
openalex publication_date 2012/06/04 · openalex created_date 2025/10/24 · openalex updated_date 2026/07/28
DNS studies of dispersed particle motion in isotropic homogeneous turbulence\n[1] have revealed the existence of a component of random uncorrelated motion\n(RUM)dependent on the particle inertia \τp(normalised particle response\ntime or Stoke number). This paper reports the presence of RUM in a simple\nlinear random smoothly varying flow field of counter rotating vortices where\nthe two-particle velocity correlation was measured as a function of spatial\nseparation. Values of the correlation less than one for zero separation\nindicated the presence of RUM. In terms of Stokes number, the motion of the\nparticles in one direction corresponds to either a heavily damped (\τp <\n0.25) or lightly damped (\τp > 0.25)harmonic oscillator. In the lightly\ndamped case the particles overshoot the stagnation lines of the flow and are\nprojected from one vortex to another (the so-called sling-shot effect). It is\nshown that RUM occurs only when \τp > 0.25, increasing monotonically with\nincreasing Stokes number. Calculations of the particle pair separation\ndistribution function show that equilibrium of the particle concentration field\nis never reached, the concentration at zero separation increasing monotonically\nwith time. This is consistent with the calculated negative values of the\naverage Liapounov exponent (finite compressibility) of the particle velocity\nfield.\n