Abstract: The kinematical law of solids particles on the screen plays an important role in its fluid flow capacity. On the basis of solid-liquid two-phase flow theory and Turbulent flow theory, the kinematical law of solids particles in inundated condition is studied. The formula of floating size of solids particles is developed. The terms of free flight and floating motions of solids particles are developed. The kinematical behavior of solids particles when they enter free flight motion is discussed. From the analysis of an actual example, the floating size of solids particles of the flow cross-sectional areas along distance is limited when drilling fluid flows along the screen. The solids particles which are smaller than the floating size, will have floating motion with the action of the vertical pulsating speed of turbulent flow. Those which are larger than the floating size will make contact with the screen, and slide, or roll and enter free flight. The height of the free flight of solids particles is not larger than the thickness of drilling fluid. The floating motion and throwing motion of solids particles are of great significance for drilling fluid flowing through the screen, so the flow capacity of the screen will be improved.

Key words: Floating motion, Shale shaker, Solids particles, Throwing motion