Sammendrag
Inertial point particles suspended in a two-dimensional unsteady circular cylinder flow at Re = 100 are
studied by one-way coupled three-dimensional numerical simulations. The striking clustering pattern in
the near-wake is strongly correlated with the periodically shed Kármán vortex cells. The particles are
expelled from the vortex cores due to the centrifugal mechanism and coherent voids encompassing the
local Kármán cells are therefore observed. The particle clustering at the upstream side of each void hole
form a smooth edge, where the particle velocity magnitude is consistently lower than at the downstream
edge of the voids. The trajectories of these particles originate from the side of the cylinder where the sign
of vorticity is opposite to that of the vortex encompassed by the corresponding void hole. The particles
are seen to decelerate along a substantial part of their trajectories. Particle inertia is parameterized by
means of a Stokes number Sk and smooth edges around the void holes still exist when Sk is increased,
although their formation is delayed due to larger inertia. Increasing inertia contributes to a decoupling of
the particle acceleration from the slip velocity, which almost coincided at Sk = 1
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