Abstract: A dimensionless formula for estimating the time-mean velocity differences between fluid and large particles has been given. The Particles are suspended in a homogeneous turbulent liquid flow. and their sizes are larger than the size of the micro-eddy of the turbulent liquid flow.A comparison between the orders of the accelerations of the eddy and the gravity shows that in a flow with considerable high Reynolds number, the dynamic force of eddy is dominant and the influence of the gravity to the motion of th...