Lift Force Acting on Body in Liquid in the Vicinity of Boundary Executing Tangential Oscillations

Abstract

The average force acting on a cylindrical or spherical body placed near the boundary of cylindrical cavity filled with liquid and executing rotational vibrations is experimentally studied. The repulsive lift force acting on solid is found and measured using the method of body suspension in the gravity field. In horizontal cavity the repulsive force provides steady state of light cylinder near the upper boundary at a distance comparable with the thickness of the Stokes layer. The heavy sphere which hangs on thread repulses from the wall of vertical cylindrical cavity under torsional vibration. The dependence of the average lift force on the amplitude and frequency of vibrations and on distance between the body and the boundary has been investigated. Results are presented on the plane of dimensionless parameters. In the examined frequency range the lift force acting on cylinder decreases exponentially with distance from the boundary. Lift force acting on sphere decreases with distance and strongly depends on dimensionless frequency of vibration. Conclusion that lift force is generated by body oscillations excited by its viscous interaction with the oscillating boundary is done. The found phenomenon is important for control of inclusions under microgravity conditions.