Experimental Study of the Solid Motion in the Vicinity of the Wall in an Oscillating Cavity

The dynamics of spherical and cylindrical bodies in the vicinity of the cylindrical wall of the cavity filled with fluid under rotational oscillations is experimentally studied. We consider (i) the motion of a light spherical body inside a cylinder under rotational oscillations and (ii) the motion of the heavy cylindrical body in a horizontal cavity under modulated rotation. In the absence of the oscillations, the bodies are pressed against the cavity walls due to the action of (i) the buoyant force and (ii) the centrifugal force. The tangential and rotational body oscillations are studied by means of video registration. It is found that the body oscillations induce the averaged lift force that is responsible for the detachment of the body from the wall at the critical value of the amplitude of the body oscillations. The oscillation-induced repulsive force is measured by the method of the body suspension in a static field of (i) gravitational force or (ii) centrifugal force. It is found that the dimensionless lift force decreases with the distance from the wall according to the exponential law. The magnitude of the lift force is determined only by the amplitude of the velocity of the tangential body oscillation relative to the surrounding fluid while the intensity of the rotational body oscillations is of no importance. Also, the lift force does not depend on the distance to the wall and increases with the dimensionless frequency ω in the studied range ω = 10 – 90. The phenomenon of the oscillation-induced repulsion of the solid from the cavity wall is of interest for the development of an effective method for the control of multiphase media under microgravity conditions.