Numerical simulation of the agglomeration behaviour of spheroidal particles in homogeneous and isotropic turbulence

Abstract Interactions between attractive spheroidal particle pairs are studied in boxes of homogeneous and isotropic turbulence. The fully resolved turbulence field and structure-resolved particle-fluid coupling regime are obtained through direct numerical simulation and an immersed boundary method. Agglomeration outcomes are accommodated through attractive van der Waals forces, suitably adapted to consider the orientational dependencies associated with the non-spherical shape. Binary particle interactions are first studied in quiescent conditions, as well as in a periodic box of homogeneous and isotropic turbulence. The latter is forced using a stochastic method, where the turbulence properties are chosen to approximate those observed in the viscous sublayer of a 180 shear Reynolds number channel flow. Differences in particle interaction behaviours are presented for the cases of disks and needles, with the role of orientation and kinetic energy in determining interaction outcomes analysed and contrasted with spheres. Results indicate that needles have the highest agglomeration propensity in turbulence, followed by spheres, and then disks. Lastly, the inclusion of attractive orientationally-dependent interaction forces promotes alignment between the symmetry axes of spheroidal particle pairs, whilst turbulence also promotes an alignment between the interacting particles when compared to the quiescent case.