A numerical study is presented for relative velocity between particle and fluid in a grid- generated turbulent flow field which is simulated by a two-equation turbulence (ke) model. Spatial behavior of this velocity is important in the determination of particle dispersion. Both linear and nonlinear drag formulations are considered in detail. Numerical results show that, for nonlinear drag formulation, the occurrence of the maximum value of relative velocity is well ahead of the location where the particle dispersion measurement is taken in the experiment. Hence, better predictions of particle dispersion obtained with the nonlinear drag formulation should be expected. it is also found that the mean square relative velocity components in the gravity direction and in the direction normal to the gravity reach the maximum values at different times.