Oscillatory Dynamics of a Spherical Solid in a Liquid in an Axisymmetric Variable Cross Section Channel

Abstract

The dynamics of a solid spherical body in an oscillating liquid flow in a vertical axisymmetric channel of variable cross section is experimentally studied. It is shown that the oscillating liquid leads to the generation of intense averaged flows in each of the channel segments. The intensity and direction of these flows depend on the dimensionless oscillating frequency. In the region of studied frequencies, the dynamics of the considered body is examined when the primary vortices emerging in the flow occupy the whole region in each segment. For a fixed frequency, an increase in the oscillation amplitude leads to a phase-inclusion holding effect, i.e., the body occupies a quasi-stationary position in one of the cells of the vertical channel, while oscillating around its average position. It is also shown that the oscillating motion of a liquid column generates an averaged force acting on the body, the magnitude of which depends on the properties of the body and its position in the channel. The quasi-stationary position is determined by the relative density and size of the body, as well as the dimensionless frequency. The behavior of the body as a function of the amplitude and frequency of fluid oscillation and relative size is discussed in detail. Such findings may be used in the future to control the position of a phase inclusion and/or to strengthen mass transfer effects in a channel of variable cross section by means of fluid oscillations.