Macroscopic Streaming Associated With Vertical, Cyclic Motion of Interface Confined in a Cylindrical Enclosure

The interface between overlaid fluids can become unstable when the fluids are excited vertically. The instability caused by the variation in the vertical acceleration is known by the name of the Faraday waves. Ito et al. (1999) studied a combined excitation problem where the fluids were excited vertically in a stationary cylinder while the interface motion was restricted by the mobility of the fluid-fluid-wall contact line. They found that, under such circumstances, the symmetric fundamental mode grows on the interface, even for excitation amplitude and frequency falling in the stable regime of the Faraday wave instability. Furthermore, they found that the contact line exhibits stick-slip-like motion for the combination of fluids and wall material used in their experiments (water and kerosene oil in a cylinder made of acrylic resin). In this paper, we describe and discuss the fluid motions associated with the excitation of fluids and interface wave. It is shown that a unidirectional flow (macroscopic streaming) is induced below the center of the interface when it is excited vertically to produce axisymmetric wave of large amplitudes. This unidirectional, jet-like flow induces a large-scale recirculating flow which extends several cylinder diameters away from the interface, a spatial scale considerably greater than the wavelength or amplitude of the interface waves, and has a time scale much greater than the excitation interval. It is shown that the phase angle between the wave-induced fluid motion and the fluid motion associated with the viscous force along the interface plays an important role in establishing the large scale stream motion of the fluids.