The Repulsion of Flat Body from the Wall of Vibrating Container Filled with Liquid

Abstract

The lift force acting on a flat body near the boundary of a container filled with liquid is investigated. The container makes tangential translational oscillations. Experimental measurement of the force is performed by the method of dynamic body suspension in the gravity field. It is found that the repulsive force acts on the body near the wall. Thereby in the container subjected to horizontal translational oscillations the body, which is denser than the liquid, repulses from the bottom. In the suspended state the body makes tangential oscillations without touching the container wall. Herein the body weight is balanced by the lift force. The hysteresis is observed between the critical transition of the body in suspended state and return to the boundary. It is found that with decrease of liquid viscosity the lift force grows and the hysteresis disappears. The theoretical model of vibrational suspension of the body in the gravity field is presented. The problem is solved in the approximation of high frequency and small amplitude of vibration. It is shown that the time-averaged repulsive force acts on both the heavy and the light bodies at a distance comparable to the thickness of the Stokes layer. The conditions of retention of the flat body in the suspended state depending on the relative density and relative thickness of the solid are found. The experimental results agree satisfactorily with the theoretical calculations in the limit of high frequencies.