DNS of a turbulent flow past two fully resolved aligned spherical particles

Direct numerical simulation with fully resolved immersed boundary method is employed to study a turbulent flow past two aligned spherical particles with different distances. A homogeneous isotropic turbulence field is generated as the inflow boundary condition and is kept developing throughout the simulation to avoid periodicity. The particle radius is about 4.7-7.9 times the Kolmogorov length and the turbulent intensities are about 12.9%, 24% and 36%. Validation is made comparing with former researchers and the distance effect is studied by comparing the hydrodynamic forces, particle induced extra dissipation, turbulent kinetic energy, and the synchronous rate of the cross-stream forces. It is shown that, under a mean flow with turbulent intensities, with enlarging the particle distances, the wake shedding behind the upstream particle is longer; the magnitudes of the stream-wise hydrodynamic forces exerted on both particles are higher. Increased turbulent intensity of the inlet condition or increased particle Reynolds number contributes to the particle induced kinetic energy and the increase of Reynolds number diminishes the difference on the particle boundary at its lateral sides. The monotonic decrease of synchronous rate of the cross-stream forces is observed with increasing particle distances when Re-p = 80, while it fails under higher Reynolds number. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B. V. and The Society of Powder Technology Japan. All rights reserved.