Based on the idea that not only the fluid mechanism but also the movement o
f the particles affects the character of the multiphase now, a new two-way
coupling model is developed. Then it is applied to the numerical simulation
of the vortex pairing in a mixing layer and it is found that the particles
impede the process of vortex pairing and reduce the Reynolds stress; the p
article with relative small Stokes number moves with the now and the partic
le with relative large Stokes number moves towards the edge, but the centri
fugal tendency is delayed as compared with the one-way coupling model.