Numerical particle-based modelling of aerosol particles in an acoustic field is performed, and the influence of the effects, including orthokinetic collision, an acoustic wake effect and mutual radiation pressure effect, responsible for the particle agglomeration is analyzed. The standard discrete element method is modified to take into account the drag force of the gas obtained using Oseen's solution and the mutual radiation pressure force. Numerical modelling of the agglomeration of two identical particles in a strong acoustic field is performed, and the results are compared with the available analytical solution and the data obtained in the experiments described in the literature. Finally, the simulation of a 2D polydispersed particle system at various sound frequencies is performed. The obtained results show that the major agglomeration mechanism is the acoustic wake effect, while orthokinetic collision plays an insignificant role. (C) 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.