Abstract: The forces acting on the dispersal particles in a swirling flow field are analyzed in an all-round way by applying the theory of two-phase flow dynamics, and the relevant forces are classified into definitive forces and stochastic forces. On this basis, a differential equation of the stochastic motion of dispersal particles is established, laying a foundation for the further study of the motion behavior of dispersal particles in a swirling flow field.

Key words: Swirling flow field, Particle, Force characteristics, Differential equation of stochastic motion