This article deals with the development of a two-dimensional dynamic model for predicting the trajectory of microparticles in an acoustic field, associated with standing surface acoustic wave, on a continuous flow microfluidic device. The model consists of two governing equations, each describing the motion of the microparticle. The model is solved using finite difference method; the solution provides the displacements of the microparticles, in the two directions, for the time duration of interest. The model is subsequently employed for parametric study. The parameters considered include the width of the microchannel, radius of microparticles, initial transverse displacement of the microparticle and volumetric flow rate. The primary application of this model article would be in the design process.