Stability of a Viscous Liquid Film in a Rotating Cylindrical Cavity under Angular Vibrations

The behavior of a viscous liquid film on the wall of a rapidly rotating cylinder subjected to angular vibrations is experimentally studied. The cavity is filled with an immiscible low-viscosity liquid of lower density. In the absence of vibrations, the high viscosity liquid covers the inner surface of the cylinder with a relatively thin axisymmetric film; the low-viscosity liquid is located in the cavity interior. It is found that with an increase in the amplitude of rotational vibrations, the axisymmetric interphase boundary loses stability. An azimuthally periodic 2D “frozen wave” appears on the film surface in a threshold manner. It is shown that the frozen wave excitation is associated with the oscillatory Kelvin—Helmholtz instability, and the stability threshold depends on a vibrational parameter. Two new vibrational effects in rotating cavities are studied accordingly: the stability (critical value of vibrational parameter) grows with decreasing the contrast in liquids viscosity; the rotation (the Coriolis force) stabilizes the interface–the critical value of vibrational parameter grows with the dimensionless rotation rate, the threshold is characterized by the product of the aforementioned vibrational parameter and the dimensionless rotation rate to some power. The discovered phenomena can be useful for vibrational control of interfaces in many technological processes, especially in the field of materials science.