Effect of axial vibration on free surface flows in cylindrical liquid

Abstract

The influence of axial vibration on free surface flows in an open cylindrical container was studied by optical in situ observation method under isothermal conditions. This ground-based experiment was performed on an electromagnetic vibrator with oscillatory frequency of 100Hz. Water–glycerol mixture was chosen as the model liquid. Results showed that small amplitude (<100μm) could generate a new type of steady streaming flows on a free surface, which were mainly driven by the combination of propagating surface wave and Stokes layer effect. The steady flow manifested various patterns according to the vibration amplitude level. Higher amplitude made steady flow periodical or turbulent, which could be characterized by the critical vibrational dimensionless Reynolds number (Nre)c. The calculated value of (Nre)c was of the magnitude of 10−2−10−1. In addition, surface streaming velocities were measured by the particle scattering technique. It was found that the velocity increased parabolically with vibration amplitude and decreased with viscosity for a fixed flow pattern.